I don't remember exactly when I heard about Microsoft Power Toys for Windows XP. I remember it was during work. If I come across interesting links or freewares at work, I will forward those links to my personal email, so that I can try those at home. When I checked my email today I found the link to Power Toys.
What I liked most is the Alt-Tab Replacement. Install this tool, and then if you press Alt+Tab, instead of usual boring switch tasks screen, you will get a more elegant window with preview of windows to switch. Try it, you will sure like it.
There are other interesting tools, too. A power calculator, Image Resizer, CD slide show creator, etc. I haven't tried all. I have installed the Virtual Desktop manager, but not sure how to use it. Still trying it.
Here is the link to download Power Toys - http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx
See a screenshot of Alt-Tab Replacement.
Download and enjoy.