<< Is there a firewall that I could use to block packets that wouldnt lag my computer to death? >>
I'm not sure about this, but I think some sort of hardware firewall would do that for you(say a router w/ firewall). When I'm at school, I get alerts all of the time from ZoneAlarm cause I'm just plugged straight in, but when I'm home on our home network (behind a router), ZoneAlarm only gives me alerts when programs on my computer are trying to get out. It might not be the most sensible solution and I'm sure there are better ones, but if you can get your hands on one, it might work for a quick fix.
-Tom