Here's a smattering of software I wouldn't want to be without on my Windows work computer:

FastStone Capture for Windows
This is a great screen capture utility.  Unobtrusive, efficient, powerful, simple & easy to use.

Winmerge
Visual differencing and merging tool for Windows.

SyncToy
Free Microsoft tool for synchronizing folder pairs.

KeePass
Secure password storage program.  Main build for Windows; builds available for Linux/Mac and handheld platforms.

CrossLoop
Secure screen sharing. Help family and friends with their computer problems.

Mozilla Firefox
It's not my primary browser but the developer plugins can be life savers.

TextPad
Powerful text editor.  I know there are others out there that developers like; this is one I've been using for years... it's quite good.  Perhaps if I have time I'll play with other text editors I've heard about.