If your computer seems to stay infected after running a virus scan it probably means the virus is reinstalling itself. Run a couple antiviruses (Avira Antivir, Microsoft Security Essentials, and SuperAntiSpyware are pretty good) in safe mode then do a registry clean up with CCleaner.
System restore doesn't really delete viruses. It just restores the computer to a previous state (usually regarding settings) and keeps your files intact.
