I had an antivirus program that really bogged down my computer so I removed it. Stupid thing to do.
I got the AntiVirus XP 2008. It is a rouge program that takes your computer over entirely, giving false positives for viruses, and trying to get you to purchase the program.
It would not let me go to any sites I could get virus removers from, would not let me use the CD drive and gave me a really ugly screen.
I thought I was going to have to reformat my hard drive.
After 3 days of staying up till 5am, I finally managed to get something uploaded on my system that got rid of it. I had trojans, worms, rootkits and a whole lot of malware. And the program I used was free. One of the best things I have ever used.
So, I guess the what I am trying to say is, keep your system protected.