Vanishing space -- what's eating my hard drive?

I run Windows XP, Microsoft Office and little else, but my hard drive space is diminishing at an alarming rate. One day, I used a gigabyte. What is going on? David Kidman

There are dozens of utilities that will show you what is using your hard drive space, and in previous answers I have suggested SpaceMonger and SequoiaView. But you need to track or graph disk usage on a daily basis, and I can't think of a good way to do that.

I've been experimenting with MouseSoft's Directory Size program, which is free for personal use. This lists directories and files in size order, but you can click the Folder+ heading to make them alphabetical. Next, use File|Send To to put them into Excel, where you can track the data after a lot of faffing about.

Someone out there must have a much better solution ...