Good Free antivirus
http://free.grisoft.com/
Good Spyware scanners/removers:
Adaware:
http://www.lavasoft.com
spybot:
http://www.safer-networking.org
Get AVG installed for a good antivirus package (scheduled scans, email scan, and resident protection) with free updates. That will help keep the real nasties back. Adaware and Spybot scan for adware/spyware and remove them. both are available free and do a pretty good job. I like to use both because what one misses the other usually seems to pick up. Spybot also has some features to sort of innoculate against a lot of spyware so they can't get in.
Most of the work I do these days involves spyware, adware/popup crap, or a virus. I can't complain about getting paid to do some work, but I try to point folks to the tools to use when I can. It is easier to prevent than to undo the damage. Hope this helps someone out there.