Skype is excellent quality free software for Voice Over IP (VOIP) telephony, although not as good since it was bought by Microsoft. It is not only free to download the software, but free to call (or be called by) other Skype users. Calls to other networks (fixed-line, mobile, etc.) cost money, but are nevertheless incredibly cheap. Skype allows not only voice calls & conferencing, but also chat (multi-participant), file transfer & video calls to/from other Skype users, if you have a web-cam. The Skype service allows you to have a voice mailbox (not free) and up to 10 fixed line numbers (also not free, and not available in all countries) which connect to your Skype account.

Skype is available for Windows, Mac and Linux, although the Linux version usually isn't usually as up to date as the Windows version.

Google Hangouts (previously GoogleTalk) is another free text chat & VOIP (voice call) service. Whilst it doesn't (yet) have all the features of Skype, it does have the advantage that (probably because it uses the HTTP & HTTPS ports) it works on networks, like my office, which have lots of security measures like firewalls, proxies, etc.

Google Hangouts is now integrated into the web-interface of Googlemail, so you can call and use IM chats whilst doing your email.

WhatsApp is another widely used Smartphone App that supports IM, multi-party chat, voice and video calls. There is a web-based interface (WhatsApp Web), allowing you to use WhatsApp on a comuputer (as long as your phone remains connected, but it only supports IM. not voice and video calls.

WhatsApp is now owned by FaceBook.

DHTML Menu tools, which work in virtually all browsers. Fully integrated into the Sothink HTML Editor. Excellent quality. It comes with an easy to use graphical widget for easily & quickly creating dynamic menus.

The dynamic menus on the previous version of this site were built with this technology, although not using the widget (I have my own Object Oriented JavaScript library (see the next entry), which makes it much easier to use, and my menus are created automatically from a database using a Perl CGI script).

Database server, SQL interface, ODBC interface, etc. For Windows, Mac, Linux & Unix. Very stable & reliable. Extremely fast. Used widely by web-hosting companies, and used for this web-site.

MySql is now owned by Sun Microsystems; luckily, Sun are equally committed to Open Source.

Integrated Office suite: Word-Processing, Spreadsheet, Presentations, Drawing, Equation Editor & Database. Able to read and write MS-Office format files, HTML & many other formats, as well as its own native formats. Has direct export to PDF. Derived from OpenOffice.

There are a few bugs and presentation issues: There is no copy-right function (<CTRL><R> in the spreadsheet); Conditional formating has a few problems, and cannot be correctly copied using the format-copy paintbrush; some autonumber styles don't work correctly. With each new release, however, it gets better, and for many people it has everything that you need.

Pretty much W3C DOM compliant. Supports multiple profiles. Includes pop-up blocking & a password manager. Very secure. Optionally includes a DOM inspector, a JavaScript debugger, an FTP Client, & various other useful add-ons. Very useful for debugging web-pages. Available for Windows, Linux, etc.

This is the browser that I use for my main web-site development work.

For Linux. This is a fully integrated email client (like MS-Outlook) with a built-in Calendar, Task List, Address Book, and local folders for storing email. It supports multiple email accounts, contacts in VCF format, LDAP address books, sending & receiving of calendar entries (meeting invitations) by email (Outlook compatible), IMAP, POP3 & SMTP. It is also possible to integrate with Exchange Server (using IMAP). Fully Open-Source. For Debian based Linux, you can get it from the repositories.

There is also a Windows version. I would not recommend it.

Browser with some very nice features. Useful for debugging web-pages. Has a few bugs. Available for Windows, Linux, etc. Fast.

One of my favourite features is the zoom function. Typing <CTRL>+<+> zooms in; <CTRL>+<-> zooms out. Unlike other browsers, Opera scales the graphics as well as the text.

Integrated system administration & tuning tool, for Windows-XP/Windows Vista. Allows you to easily edit your Auto-Starts (Registry & Auto-Start folder), tune your memory use, optimise your system for particular tasks, etc.

The more recent versions also include a virtual desktop tool. This allows you to define a number of virtual desktops, which you can use to stop your task-bar getting cluttered when you have a lot of windows open.

Easy to install & use Linux. Available in Server (without GUI) & Desktop versions. Recent versions support KVM (Kernel Based Virtual Machine) to run other Operating Systems (other Linux versions, Windows, etc.) in a virtual machine window on the Linux Desktop. Supports 32 bit & 64 bit CPUs, multiple CPUs, etc. Automatic update service. Easy to use GUI based Package Manager to find & install new software from an enormous range of free and open source packages. There is also Ubuntu Studio, for media work.

For the those of you who are less tech-savvy, there is a tool (Wubi) (part of the latest release) which installs Ubuntu Linux as if it were a Windows application (with normal Windows-style uninstall too) in a virtual disc (a file on the Windows file system). It doesn't get any easier than this. If you decide later that you want to have it on a real disc partition of its own, which runs faster, there is another tool (LVPM) to do just that.

There are many applications which can do exactly the same as your familiar Windows applications, including reading and writing Microsoft format files. There is also Wine, which will run programs written for Windows, under Linux; usually they run faster under Wine & Linux than under Windows.

One nice thing is that there is no enforcement of DVD region codes. If you have a DVD which has a different region code than your locale, you can play it (or rip it) on a Linux computer, when your DVD player won't play it. In Windows, you can change your DVD drive's region code, but only 5 times.

ProxMox VE (Virtual Environment) is a ready to use virtual machine envronment. It is based on the Debian Linux operating system. It has a web-based interface to allow you to easily set up and administer virtual machines.

If you have a PC set up with dual-boot, then you should definitely think about ProxMox instead.

You can use ProxMox VE to install multiple virtual machines (e.g. Ubuntu Linux, Windows-XP, Windows-Vista, etc.), all running on the same hardware at the same time.

You can set up a cluster of ProxMox servers, so that you have fail-over. You can migrate a virtual machine from one ProxMox to another.

Technically, of course, this is not an operating system, but it is a great accessory for Linux.

PlayOnlinux was created for people who want to play Windows games on their Linux PC. Actually, it is an installation assistant for installing Windows applications under Wine, on a Linux machine.

Wine is a fantastic emulation tool for Linux, which allows Windows applications to run under Linux. They usually run faster than under native Windows. It can, however, be difficult to properly configure some applications to run under Wine. PlayOnLinux provides a GUI & a set of scripts to install & correctly configure a huge list of applications to run under Wine.

The list of supported applications is huge, and growing all the time. There are lots of games, but also scripts for MS-Office (2000 & 2003), Internet Explorer, Safari, iTunes, etc.

X11 server for Windows, based on Cygwin from SourceForge. Allows you to open either individual X11 applications (which open in native windows on the MS-Windows desktop) or a whole X11 desktop from within MS-Windows. Very quick and easy to install, and easy to use. A little slow on client systems with lower performance graphics. In addition, you need something like putty (configured for X11 forwarding) to open a session.

When I use Windows (only when I have to, for example when I am testing a web-site with Internet Explorer & Safari) I use X-Mins a lot, to access Linux tools on my server.

Excellent & easy to use DVD copy program, for Windows. Will shrink (compress) the data to fit the target DVD. Can interface to NERO burner. There are options to remove soundtracks & subtitles in languages that you don't want. You can also remove region coding. Due to legal reasons, you will need to do a web search to find a host from which to download - make sure it is genuine (money is never charged for the real DVD Shrink).

DVD Shrink works flawlessly under Linux & Wine, at awesome speeds.

Excellent & very easy to use decrypting DVD copy program, for Windows. It will copy encrypted DVDs and ISO disc images - an excellent program to use if DVD Shrink is unable to read a disc. There are regular updates.

On Linux, I currently have an older version, as the newer versions don't seem to work well under Wine.

Excellent & easy to use Music CD Ripper, for Windows. Can connect to online database to find CD information (Artist, date, track titles, etc., which is automatically stored as ID3 tags {file properties} on each of the output files). Converts to various formats (needs external LAME encoder to convert to MP3).

After some fiddling about, I finally suceeded in getting it to work under Linux & Wine. Check these forum entries to find out how: getting EAC to work under Wine, getting EAC to work with the Lame encoder under Wine.

The standard MP3 encoder. Available for Windows, Linux, Unix, etc. SourceForge only distributes the source code, but there are various sources (listed on the site linked above left) for binary versions (e.g. RazorLAME & WinLAME).

I use RazorLAME (for Windows) on my Linux machines (running under the Wine compatibility software). It operates flawlessly, and at incredibile speed.

The GIMP (GNU Image Manipulation Program) is the ultimate graphics editor. It will edit or create virtually any format of graphics file (including animated GIFs), and convert from one format to another. It has built-in functionality for creating button graphics, for web-site menus. It has its own scripting language (Scipt-Fu), so that you can automate functions that you need to perform often.

Originally created for Linux, there is also a Windows version, which is indistinguishable from the Linux version.