My experience with Windows is whenever you got a virus, the best way to fix it is do what Allan suggested - a clean reinstallation. The reason for that is depends on how vicious the virus is, some of them might install vicious files(codes) deep into the OS, no matter how you try to clean it up, there is no guarantee and no way to tell whether you have all malice files removed thus will cause problems in long run. So make sure you have backed up all your important documents at all time.
The other strategy I suggest to my customers is, if you are somewhat tech savvy, try to buy a barebone external hard drive of the same size as your internal drive, once you do a clean reinstallation, before you even get on the net, make a clone of the boot drive to your new external drive. This way you can preserve all your documents and applications, thus provide you a way to do a rapid recovery without going through the painful process of reinstall all your applications. All you need to do is to swap the external drive with the contaminated internal drive - the boot drive.
Hope this helps.