Firewire interface card - PCI or PCIe?

Hi there,

I want to buy a new firewire interface. The onboard thing on my Asus P5K
seems to have lots of electrical noise on the ground and occasional
dropouts (unchangeable and shared IRQ), which I hope will get better
with a dedicated internal card.

My mainboard can take both, PCI and PCIe. Do you think these two options
differ in their likelihood of providing dropout-free data transfer?

Thanks for any thoughts,

Boris