Lowest Latency Firewire?

[Lyxtwing]

I'm building a DAW in the next week or two and need to pick a motherboard. Looking at a P35 board that has support for every item I currently own or plan to buy, but the one I am looking at lacks the firewire jack my audio interface needs.

My question is simply will I get more latency from a PCI card than an on board firewire jack for an off board audio interface? Will the make of the firewire card make a difference? Looking at an nGear, or using an audigy's firewire port as I do now. It seems fast enough, but it'd be a bit of a pain to find out later that I should have gone with on board.

Any advice would be helpful,
Lyxtwing