If you encounter a virus attack, do something at once to prevent the spread of the virus to your system. First, concentrate on the kind of virus to remove the malicious code. There are tools which are available online tailored for that specific virus causing the damage. Next is to see the range of the damage done. If the operating system is completely destroyed, you will have to reinstall. This can be done by using the quick restore CD that comes with your computer. But before you start the process, make sure that you have the necessary information like licenses, registration and serial numbers available. Then do a thorough virus scan of your network. Be sure your anti-virus software is recently updated and that your security patches are up-to-date to prevent future attacks.