I'm new here, so please be patient with me all you vetrans. I finally had my first encounter with a virus, and had a problem similar to MetalMaggot's. Through my own carelessness, I downloaded the YAHA.K worm. It proceeded to shut down my Norton antivirus and firewall before I could do anything about it. To get rid of it, I was forced to go a free online virsus scan where I was able to determine the type of worm, and also the location of the "new files" and processes running on my PC. I was unable to delete the files. I kept getting a message telling me that the file was in use or something. Using cntrl alt delete did not help because the window showing the running processes disappeared almost immediately, and so, I was unable to end the processes. I had Norton Utilities on a CD which contained a process viewer. Thankfully, it worked, and I was able to shut down the offending processes, and delete the files. Interestingly enough, I re-scanned a second time and found some other residual "garbage." After the third scan, all was clean, (at least I hope so). The final hurdle was restoring the registry back to its original state. I was unable to use programs with an .exe extention. For anyone interested, the site I went to was: http://www.trendmicro.com/en/home/us/enterprise.htm
You can scan for and get information on any virus, (including how to get rid of it).