If you're worried about viruses or spyware, I found a forum today that specialises in ridding computers of both. They have a step-by-step guide and links to four great free programs. You can also post a log result in the forum and their members can tell by looking at it if you've got any problems in your computer system.
http://www.webuser.co.uk/cgi-bin/forums/sh...sb=5&o=93&part=
Good luck!