dont use xp firewall...its just my preference i dont like it because a freind of mine had his turned on automaticly by his isp.
i want total control and for that i trust the sygate and nortons personal f/w
those are the firewalls i would recomend for anyone wanting security..although i will say that no system is impossible to crack with the right tools and enough determination the right person could find the right door to come in....just dont leave the door wide open by not having a firewall.