I know you asked me about this one.
I installed SP2 on serveral PC's at home. And have just got ICS working again.
I have XP SP2 with ZL and the MS firewall on the main PC with USB broadband. Turn off ZL and my son can get to the internet, back on and he can't........Control
While the MS firewall will still provide some protection.
Both machines have AVG which is set to auto update.
Regards
Nick