Backdated's famous anti-virus post has gone missing! This thread is a replacement for that immortal post. Feel free to reply to this; add onto it, please. I only remember part of it.
Tools to downloadCCleaner for removing caches, temporary internet files, and other junk nobody uses.
SpywareBlaster to protect your system from spyware.
AboutBuster to get rid of the HomeSearchAssistant parasite
HijackThis to eliminate hijackers and leftover traces of viruses - download and install to it's own folder!
Killbox to delete those viruses that just won't go!
Panda - a decent AntiVirus software.
That's all I can remember for now. Add on to it!