Beyond Virus Checkers
Even with heuristic scanning, a method for detecting viruses with unknown signatures, virus checkers are basically reactive. Of course, you should install a virus checker and update its engine and virus definitions regularlybut don't stop there. You should also follow the five suggestions listed here:
1. Installing operating system patches is time-consuming but worthwhile. Select Windows Update in your Start menu, or go to http://windowsupdate.microsoft.com and click on the Scan for updates link. A script will figure out exactly what you need and present it in a list. Just select the items you want and click on Install Now.
2. Worms can propagate across network shares if you write-enable shared directories that contain executables or crucial system documents. You should never write-enable a directory that contains anything but end user documents.
3. Binding file sharing to TCP/IP on your Internet-connected device gives anyone on the Internet access to your hard drive. To prevent this, open the Network settings dialog, right-click on your Internet device, and choose Properties. The TCP/IP protocol will be selected. Make sure that the service File and Printer Sharing for Microsoft Networks is not selected.
4. Most malware is spread via e-mail attachments. A personal firewall that quarantines potentially dangerous attachments can keep your system safe and prevent viruses from spreading.
5. Lastly, you should back up regularly. There are more than 500 new viruses discovered each month, so be prepared.