ss1, norton is a piece of crap. Do yourself a favor and get AVG (www.grisoft.com). They have a free version and even the virus database updates are free. It's also smaller than Norton and doesn't clog up your resources. Norton is a memory hog.
AVG Free Edition is here:
http://www.grisoft.com/doc/40/lng/us/tpl/tpl01
That said, you still need a program that scans for malware, spyware, and the like. Ad-Aware is a good one.