ShoobieRat is right, Norton is only a resource hog in the following situations.
*You dont know how to configure a program.
*You dont know how viruses work.
*You are not a power user.
Norton Auto-Protect (the program you are refering to as a resource hog) is simply for people who dont know how to safely use computers and dont know what to look out for. You can actually turn Auto-Protect off, using no resources and still scan a file for a virus if you can believe that.
Symantec corporation (Norton) is one of the companies that actually hunts viruses, so if AVG or whatever recieves a virus definition, they are probabily getting the definition from Norton. And no program can detect ALL viruses, Virus makers are always one step ahead.
Delphi Enterprise 6 - 7
VB 6.0 - 2005 EE