It seems to be enough (and more than that!) in the antivirus realm, however I would prefer to have only one real time scanning active at a time, and call all others manually, because often antiviruses may conflict between them when a virus is found and both try to remove or quarantine it.
I would add a firewall to this combination, blocking all traffic except that you know you need, even the Windows built-in might be enough. Also remember to always use a standard use account for the normal operation and if you want to use UAC, always put it to the highest level.