Anti-Virus

AVG
The newer versions are much improved.

Audio Recording

Audacity
Quite powerful audio recording and editing software.

Backup

Mozy
Personal users get 2gb for free, always backup your stuff!

CD and DVD Burning

CDBurnerXP
You don't need nero for burning stuff to a disk!

DVD Video Authoring

DVD Flick
Convert your video to dvd format and burn, simple.

Email Client

Thunderbird
The best email client and rss reader around.

File Compression

7-Zip
No need for winzip or winrar.

File Transfer / FTP

FileZilla
Powerful ftp client, use it all the time.

Firewall

PC Tools Firewall Plus
A valid alternative to ZoneAlarm.

Image Mounting

Magic Disc
Simple tool for image mounting.

Imaging

Paint.Net
It can't do everything (like photoshop) but most common imaging tasks it can handle.

Internet Browser

Firefox
Used it for years, never looked back.

MP3 Tagging

MP3Tag
Organise your mp3's tags, get artwork from Amazon.

Office Tools

Open Office
Not as user friendly as MS Office but then it is free.

PDF Creator

PDFCreator
Print to pdf, easy.

PDF Reader

Foxit Reader
A simple and fast alternative to the bloated adobe offering.

Portable Software

Portable Apps
Filezilla, Open Office plus lots more on your usb.

System Clean up

CCleaner
Removes old internet junk and temporary files.

Stretch Reminder

Big Stretch Reminder
Reminds you to take regular breaks.

Text Editor

Notepad++
Great text editor.

Torrent Downloading

UTorrent
Clean and simple torrent client.

Video Player

VLC Media Player
This will play any kind of video.

Virtualisation

Virtualbox
Useful for testing and trying out linux distros.