I have the same card, and have some experience installing it. The hardware in that card, includes HDMI sound output. However, that hardware is not supported by the AGP bridge chip in the card, and for some reason, the sound part of the card defaults to enabled upon power-up, rather than disabled. Therefore, it generates a steady stream of interrupts that bog down the processor. (With the proper drivers installed, it disables the sound output, and thus stops the interrupt stream.)
Mine was the VisionTek card, and it required using the drivers that came on the CD for XP with it. I at one point was able to use the updated drivers off of VisionTek's web site, but at some point, they updated those drivers, and then they simply resulted in a black screen when booting Windows with them (the newest ones) installed.
Rig(s) not listed, because I change computers, like some people change their socks.