lost hd space

I just had a computer build with a 200gb hard drive.After i installed windows 2000 pro something happened..When I tried to download aol 9.0 i get a message saying i fdo not have enough memory/hd space..I think i loaded it to the wrong opartition. So tell me should i reformatt my hd then reinstall windows..I know practically nothing about computers..what i kknow i learn on the fly from you guys on sites like this..Please help