I would suggest you better PCTOOLS PLUS FIREWALL. I run it without any problems both on Vista and XP PRO SP2. Comodo 3 is for people that like to break their head and live bad existence!
He can test Online Armor free(or paid),CFW, PC tools, ZA free(or paid), and then he can choose himself.
But i think you must not offense or blame comodo users, no?
I use CFW without problems, i'm very happy with it and i like have all under control.
If you use PC Tools FW without problems, and you are happy with it, All right, but please, no ofence another FW users.