Let's see...what I use all the time:

XP Pro
FF 3.6
Online Armor Pro
ESET NOD 32 v4.0
Thunderbird 3.0.1
Xnews
Eraser
...and commercial graphics tools

Nearly all the time:

Ashampoo Burning Studio 9
Photoshop CS2
Capture One 5.02
Lightroom 2
KMPlayer
Malwarebytes Pro
CCleaner
Revo Uninstaller
jv16 Power Tools 2009
Virtual Box
TeamViewer
Acronis True Image 2010

...and utilities, data recovery tools, etc. Probably an equal split between free and payware.