It sounds like you installed a lot of programs onto your C:\ drive including games. All your game saves are also saved to the C:\ drive (C:\Documents and Settings\[your profile name]).
It seems you need to do a lot of cleaning or re-install Win XP and install your games onto a separate hard drive.
- My Win XP takes up 6GB on my C:\ drive, leaving about 16GB of free space.
- I install all my games on the D:\ drive which is the same physical hard drive as the C:\ drive, I just created a logical partition for organizational purposes.
- The page file (2GB - 4GB) is saved on a separate physical hard drive. I'll just call it the E:\ drive. I have 4 physical hard drives in my PC.