I have been an avid user of many types of software for many years, and am always looking for new software to try, so perhaps I can help you save time in selecting software. I won't include links as they are a pain keeping up to date, but allow the reader to Google them if interested!
All software mentioned is FREE unless otherwise stated.

Web Browsers

My browser of choice is Firefox. It is fast, heavily customisable with a myriad of add-ins and is kept up to date with fixes for security issues better than it's competitors. I also occasionally use Opera and this would be my no.2 choice, although some way behind Firefox. I only use IE when I absolutely have to, i.e. software updates. I've also started using Chrome for the odd Flash game.

System Tools

The most important software I use is Acronis TrueImage, which takes my backups while I sleep, but sadly isn't free!

These are the FREE system software tools I use most often:-

• Gparted - Excellent disk partioning tool - allows you to dynamically resize partitions
• Supergrub - Excellent tool for restoring grub boot menus, particularly when overwritten/destroyed by Windows
• Comodo Firewall - Excellent firewall
• AVG Free edition - Virus protection
• MagicDisc - Virtual CD/DVD drives to play disk images
• TrueCrypt - An encryption tool to create secure virtual disks
• UltraVNC - Great software to run a PC remotely - I can make changes on my other machines without leaving my main machine!
• AdAware and Spybot Search & Destroy - two great apps to remove unwanted nasties from your machine
• Eraser - Excellent piece of software to securely delete anything from your machine
• Hexplorer - Hex viewer/editor for files
• AutoIt - Script automation tool
• DirSyncPro - Keeps copies synchronised
• Auslogics defrag - useful tool to defrag those hard disks

Graphics

An excellent free graphics package with most of the features of Photoshop is GIMP. Apophysis is an excellent fractal generation program, if you're into that sort of thing. Inkscape is a well featured vector graphic program which I use occasionally. My favourite graphics software is CorelDraw/Paint, but that costs serious money.

Games

The last game I bought was The Witcher, which I can thoroughly recommend. I still occasionally play Guild Wars and Oblivion, both of which were well worth the money. Guild Wars is particularly worth mentioning as once you've bought the software playing on their servers is totally free, which makes for exceptional value.

Recently I've been trying a FREE MMORPG Runes of Magic, which is similar to WOW. I've been fairly impressed and can recommend it if you don't want to pay a monthly fee for an online multi-player RPG.

Media - Movies, Music and Sound tools

Winamp is my music player of choice, although the standard Windows media player is OK. For movies I prefer Media Player Classic or VLC. For editing sound files you'd struggle to find anything better than Audacity. If you want to convert media then MediaCoder is a good choice, although it can be daunting at first with all the options available.

Educational software

I don't use much educational software, but have found Celestia and Cartes du Ciel quite good astronomy packages.

RSS software

Having tried out over a dozen RSS readers I primarily use Google Reader but also use Snarfer

Other software

Thunderbird is an excellent email client which I can recommend. Sadly the calendar add-ins available are not yet good enough for serious use, but probably adequate for simple home use.

OpenOffice is an excellent alternative to MS Office unless you've invested in using macros in MS Office, as translating them will be a challenge!

I use Usenet quite a bit and use XNews primarily for text groups and Binary News Reaper(BNR) for extracting binaries. BNR hasn't been updated for a while and does has a few idiosyncrasies but I find it quite effective and not found anything that works better for me.

I use XAMPP to run a local webserver to let me prototype my website locally before using FileZilla to upload the files.