system
5
very l33t 
NO problems with Avast 4.5 either.
The only thing new I noticed,…from my point of view,…is the “network shield”,…however you cannot configure anything,…really,… ::).but I guess that is predefined for the home user!
The fact that it supports more p2p and instant messengers is a good thing! 
I am using Avast for about 1,5 years now,…and I haven’t regret one second! 