I discovered I've got an unknown NexGen Microsystems audio controller. I searched the 'net a lot, but couldn't find a driver for this. Also, from what I understand, LinuxMCE has it's own rules with the drivers so I didn't want to mess with them too much.
I've got a nVidia Geforce3 TI 200, who's drivers seem to be working fine.
I would suggest upgrading your nVidia card (same goes for your sound card too)... Look on the Wiki or search for other threads here... but nVidia 6100/6200 or 7300 cards are good cards to look at and are well supported.