If you're running XP and you haven't seen these already you should have a look at the XP Powertoys. They're useful and occasionally fun utilities Microsoft put out for more advanced windows users. There's the essential Tweak UI, a graphing calculator, an advanced alt-tab screen (that shows a preview of the window you're alt-tabbing to - this is apparently a standard feature of Vista), tools for managing RAW files and lots of other cool stuff like that. It's well worth a look.