Tiposaurus

Here's a little privacy hack for users running Windows XP. If you have a hard drive with some kind of mildly sensitive information on it, then you can stop it appearing in My Computer but you'll still be able to access it by installing a utility that Microsoft created, Tweak UI. It allows you to tweak many smaller settings which don't feature in any of the standard Windows preference menus. One such option is to control which drives appear when you open up My Computer and which don't.

Once you've installed Tweak UI then you have to find and expand the My Computer node in the tree menu on the left, then select Drives. Once you've done that, then you'll be shown drives A to Z (even if they're not actually drives you have - if you later install a hard drive W: then the setting here will determine if it is shown then), each with a check box next to it. Uncheck the drives that you don't want to be shown. To access the drive once you've done that then you'll need to enter the drive letter, eg C: in the address bar of Windows Explorer.
I should point out that this isn't a secure solution - it doesn't do anyone to actually stop anyone accessing information on the drive, however it can be useful to prevent friends and coworkers stumbling upon information you'd rather they don't see.

Although I've mentioned that this is a privacy tip, that's not what I use it for. I have a dual boot set up with another version of Windows, though XP is my main one, and the drive from that other install shows up in My Computer. I use Tweak UI to get rid of the drive letter there, purely for tidiness. I know I could just remove the drive from that version of Windows through the Administrative Tools in the Control Panel, but it is sometimes convenient to have access to it so I use this method. Tweak UI is good at resolving small annoyances such as that.