Suggested reading:
"Why is a dedicated FireWire card with a Texas Instruments (TI) chipset important on a PC"
http://avid.force.com/pkb/articles/en_US/FAQ/en404647 Important quotes from the article above: "There are several FireWire chipset developers that build chips that are significantly cheaper than Texas Instruments, and for this reason, PC manufacturers are starting to use these less expensive chipsets. Unfortunately, many of these other chipsets are not as reliable as those manufactured by Texas Instruments. M-Audio cannot simply say only use Texas Instruments chipsets, because some of these other controllers actually work very well, and M-Audio does not want to endorse any particular manufacturer. "
"Even if your motherboard has an on-board FireWire controller with a Texas Instruments chipset, you may encounter problems because all onboard devices, including the FireWire controller, are run through the Southbridge of the processor. This means that there is a lot of traffic that the FireWire signal must compete with for access to the processor (all USB, onboard audio, onboard video, serial ports, network controllers, etc...). Data coming from all of these devices creates a bottleneck and greatly increases the chance of the FireWire signal being interrupted. The interrupted data is dropped to maintain the delivery time of the rest of the data. When too much data is dropped, the audio signal may be appear as distorted, completely dropped, or the computer may even drop the connection with the FireWire audio device. To avoid this on a PC, we always advise installing a dedicated FireWire card. This is because the PCI bus runs to the Northbridge of the processor. The Northbridge provides more reliable access to the processor because it only manages the data from the PCI, AGP, and memory."