Any free software that you'd recommend? Anyone got free software they'd like to recommend? Post it here and I'll keep the first post updated with the most recommended. All must work on Windows as a minimum requirement... hopefully this can become a useful resource. Here's a few obvious ones to start with:

Office Suites:

• Open Office - is a multiplatform and multilingual office suite and an open-source project. Compatible with all other major office suites, the product is free to download, use, and distribute.

Web Browsers:

• Firefox - award-winning, free Web browser is better than ever. Browse the Web with confidence - Firefox protects you from viruses, spyware and pop-ups. Enjoy improvements to performance, ease of use and privacy. It's easy to import your favorites and settings and get started.
• Opera - most full-featured Internet power tool on the market, Opera includes pop-up blocking, tabbed browsing, integrated searches, and advanced functions like Opera's groundbreaking E-mail program, RSS  Newsfeeds and IRC chat.

Email Clients:

• Thunderbird - delivers. Enjoy safe, fast, and easy email, with intelligent spam filters, quick message search, and customizable views. Brought to you by Mozilla, Thunderbird makes email better.

Image Manipulation:

• The GIMP - is the GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages.
• Paint.NET - is image and photo manipulation software designed to be used on computers that run Windows 2000, XP, Vista, or Server 2003. It supports layers, unlimited undo, special effects, and a wide variety of useful and powerful tools.

Image Viewer

• IrfanView - is a very fast, small, compact and innovative graphic viewer for Windows 9x/ME/NT/2000/XP/2003. It is trying to be simple for beginners and powerful for professionals.

Media Players:

• VLC Media Player - a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, ...) as well as DVDs, VCDs, and various streaming protocols. It can also be used as a server to stream in unicast or multicast in IPv4 or IPv6 on a high-bandwidth network.
• Winamp - long standing media playing software that can do pretty much what Windows Media Player does but with a large array of plugins and visualisations. Also the home of Shoutcast streaming. Has unfortunately been overshadowed since AOL bought the company.

Audio Players:

• Quintessential Player - is all about you. With its new extended freeform skinning engine and plethora of feature extending plugins Quintessential Player can be whatever you want it to be.
• dBpowerAMP Audio Player - Illustrates fantastic dBpowerAMP Audio Player (dAP), if ever there was a complete player this is it! dAP plays Mp3s, WMA, Ogg Vorbis, Monkeys Audio, Real Audio, Wave and Midi.

Audio Converters:

• Audacity - is free, open source software for recording and editing sounds. It is available for Mac OS X, Microsoft Windows, GNU/Linux, and other operating systems.
• dBpowerAMP Music Converter -  nicknamed the Swiss knife of audio Music Converter is a must in the world of audio, transforming your PC in to a true multimedia tool.

CD Rippers:

• CDex - a CD-Ripper, thus extracting digital audio data from an Audio CD. The application supports many Audio encoders, like MPEG (MP2,MP3), VQF, AAC encoders.

File Archivers:

• 7-Zip - is a file archiver with a high compression ratio. Supported formats for packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR, unpacking only: RAR, CAB, ARJ, LZH, CHM, Z, CPIO, RPM and DEB.

FTP Clients:

• FileZilla - is a fast and reliable FTP client and server with lots of useful features and an intuitive interface.

Instant Messaging:

• Gaim - is a multi-protocol instant messaging (IM) client for Linux, BSD, MacOS X, and Windows. It is compatible with AIM and ICQ (Oscar protocol), MSN Messenger, Yahoo!, IRC, Jabber, Gadu-Gadu, SILC, Novell GroupWise Messenger, Lotus Sametime, and Zephyr networks.

I recommend Db Power Amp.  It's a great little music player and ripper.  It also supports the open source FLAC format.  FLAC is a "lossless" audio encoding.

One think to be aware of with dBpowerAMP is that the mp3 encoder is 30-day only. I used it quite a lot when doing my Star Wars stuff, to convert the captured waves to mp3s.

Being a Cheap Sod, I find the free everything. Heres a few gems.

Quintessential Player - Awesome WINAMP alternative, loyal fanbase, plenty o' skins and plugins plus support for just about every audio codec, and can rip too. (www.quinnware.com)

CDeX - MP3 ripping tool, interface is a little cluncky however. very powerful, and MP3 quality is top notch. (http://sourceforge.net/projects/cdexos)

Ifran Viewer - Handy little picture viewer, lots of plugins avaliable and has very good loading times and a few picture rendering tools (http://www.irfanview.com/)