I'll second TreeSize - very effective at finding those several-hundred meg folders that you forgot about.

My cousin told me that her drive was full and she started deleting documents and stuff to make more room but it didn't seem to have any effect. I found the problem - a 900Mb file in her Temp folder, seems she scanned an A4 page at 19,200dpi and it crapped out and left the file there!

At the time she had a 1.6Gb hard drive and 5 kids who doodled a lot in paint and saved them as BMPs so it was pretty full.

Gareth