Control the Recycle Bin
Paul Staley asked how to control the Recycle Bin's hard drive space usage.
When you "delete" a file, Windows doesn't actually delete it; the OS moves the file to the recycle bin. That way, if you change your mind, you can easily recover it.
You pay for this safety net in hard drive space. A file in the recycle bin takes up as much room as it did beforehand, albeit only temporarily.
You can control how large the Recycle Bin gets before it starts actually deleting the files inside it. You can also turn it off, so that Windows truly deletes files when you click Delete. (That's kind of dangerous, however, for obvious reasons. See Recover Missing Files for other ways to--hopefully--recover files no longer in the Recycle Bin.)
To change your Recycle Bin settings, right-click the Recycle Bin and select Properties. If you're using XP, you'll find a slider bar which you can use to control how much of the drive can be used by the Bin. Vista and Windows 7 users can enter another number into the ‘Custom size' field.
To turn off the Recycle Bin, check Do not move files to the Recycle Bill. Remove files immediately when deleted.