John is correct, you can go to
www.symantec.com (or McAfee's site) and use their free virus removal tools, even if you don't own their product.
My brother's was unaware that his friend who owned a local computer business, who built and sold him a computer with software did not install any virus program (would never recommend him myself), and couldn't get rid of the virus for him when called 2 months ago. I went to symantec on his computer, ran their free virus checker, it found the virus, ran their free removal tool from the site, and computer's been fine ever since.
Of course I told my brother, go out tomorrow and get a virus program, especially with a cable modem.