X1900XT: PCI Bus choking? pros help!

Greetings knowledgeables ,

Does anyone know if there is a way to change the latency of my PCI express X1900XT so that it allows room for my 1394a firewire soundcard (MOTU Ultralite) to function properly during 3d games? As it stands, all of my 3d games sound distorted and garbled, as if the video card is hogging my whole PCI bus. The sound is fine with my onboard soundcard.

I'm not entirely sure if this is the issue, but it is my best guess. It happens most severely with Oblivion, and less severely with older games (half-life 1 runs fine!). My FW card has its own separate IRQ.

Any help would be supremely appreciated!

My system:

E6600 2.4 Core 2 Duo
Gigabit GA-965G-DS3
ATI Radeon X1900XT
2 GB Geil 800Mhz dual channel
MOTU Ultralite
SIIG 1394a Texas Instruments chipset