Alrighty, I have an P5N-E SLI motherboard (650i, nF4 southbridge) and I've been using the hardware firewall (ActiveArmor) quite happily for the past year without incident. I've also been keeping the Windows firewall (XP SP2) active for whatever loose protection it may offer.

My question is this: Is it best to have them both active? I've never had any problems with interference (aside from the nF4 firewall occasionally raising my ping in an online game) between the two, but I'm wondering if keeping the Windows FW on creates a security hole that could bypass the hardware firewall or something.

Perhaps this is undue concern. As much of a hardware lover as I am, I don't have much experience by way of security. Again, I haven't had any problems as some users have reported. The only BSOD I've received came from me accidentally assigning two masters to the same IDE cable. xD

Should I turn off the Windows firewall or just leave it be?

Doesn't matter how many firewalls you have as long as they don't conflict or overstep each other's responsibilities. The ActiveArmor is a chip-based, so it should be blocking incoming, whereas your Windows firewall is software-based, and it should be blocking outgoing. Think of ActiveArmor as a hardware router. I don't know if XP can do that. Vista can do both or either incoming & outgoing.