NIS is really absurd.I am using quick heal >its really very good.The virus which Norton,Mc afee,pc cillin couldnt handle was cured and deleted by Quick heal.The virus like windows GY a terrible one was deleted.Even I used to face the same problem.No internet connectio if new PC cilli and NIS is installed.So my vote goes for QUICK HEAL which never hinderd trhe old PC which was having 256mb of ram and even my new PC having 2 gb of ram!!