Ok. First, Goto
http://housecall.trendmicro.com/ and do the online virus scan to make sure you're free of the virus. (Sometimes a virus can mess up your antivirus software if you installed the software after the infection.)
Next, what kind of operating system are you running? If you are currently running XP, you can do what's called a "repair install", which if done correctly will allow you to just fix your windows system and keep your other files intact.