Is avast! antivirus effective enough over fighting VIRUSES.. Since, it is freeware, I doubt its use. Norton Antivirus is very heavy on my system resources and I need to find an alternative as a home user with practically little internet use. Should avast! be trusted? I hve ZoneLabs firewall installed and also Ad-aware for fighting hackers and adwares.. So, all that is left is a good antivirus agent..