I use Ad Aware and I also use AVG Anti-Virus for viruses, which is a freeware program I highly recommend for anyone who wants a good, free virus scanner. It's saved my computer a great number of times.
I use Macafee as firewall/viruscan, which keeps on detecting Portscans and shit coming from this site. I also use Spybot: Search and Destroy, which keeps all the spyware off and keeps my computer running smoothly and keeps it clean.