I agree with lurkswithin, format and re-install. It will probably take you less time and it's the only way to be positive there is no trace of any malware left. Just put in the recovery disc the computer came with, turn it on and choose format and re-install.

Side note- I have heard of virus's that store files like these then serve them from your computer. The reason for someone wanting to do this is either bandwidth and or illegal content. Could be a very serious problem, not just some files taking up space.