Hello Dnj
If it’s in the vault its safe
I have AVG Free on my Laptop, and we also recommend it to domestic customers, (For most people it is fine) however it does have a limited range of Scanning Modes, and it is not as proactive (Stopping viruses getting in the first place) as the paid for security suites, (It also has issues with Networks) this is why there is a paid for version of AVG, which does not have any of the scanning modes disabled.
Regarding Norton; since the 2005 version it is now efficient with system resources, and so causes a minimal. Performance hit on the computer.
I have Norton installed on my main machines, (They are all networked) with the exception of Windows Vista, which has PC Cillin. (The only one that currently works with Vista)
BTW The latest MacAfee programs really eat up system resources.
Hope this helps

Bill