As I think I said before I am constantly installing and re-installing operating systems. In the last week and a half I've re-installed Windows and Linux at least three times. Every time I end up losing data on my hard drive.
So I just bought a second drive -- a small one of just 80 GB, just for operating systems. So from now on I can keep my files safe on their 750GB drive and play musical chairs with operating systems on the 80 GB drive.
I should have done this from the start.