A law firm I used to work for would use a free utility from Trend Micro called PC Cillin. This works great, I still use it at times on top of my virus protection software that I’ve paid for. If you click on the following link, you should be able to use PC Cillin for free. There should be free scanning links right on the home page.
http://www.trendmicro.com/en/home/us/home.htm

eTrust by Computer Associates is free.

Try AVG by Grisoft. Works great. No charge, either. My tech downloaded it from a disk, but if you typed AVG into your browser, I’m sure there will be a link to click on and get it.
You can also check with the Kim Komando Show. If you sign up for free newsletters she has great tips for problems and links to free stuff.

McAfee also has one.http://us.mcafee.com/root/runapplication…

try avg.com or download.com and do a search for free anitvirus and removal…

Yes there are many.http://www.avast.com