Adding a firewire card: PCI or PCI-E?

The PCIe bus is faster than the standard PCI, and the cost of an adapter card ranges from 10$(PCI) to 20$+(PCIe). If the extra 5-10$ is going to ill your budget get the PCI, otherwise PCIe is the way to go...

The standard PCI slot has ~100MB/s usable bandwidth shared between all devices on the bus, which is about twice as much as FW400 so there should be no problems unless you have other high-bandwidth devices on the PCI bus.

no benefit, PCI card ( firewire) should at PCI , because the card works only transfer data from DV to PC by the way of manual (record)

Sounds like PCI-E FW cards are for people that don't have PCI slots in their newer motherboards. Good news.