I wouldn't get a Nvidia motherboard. They usually 'crackle, snackle, pop' on them and when you call Nvidia, they will say it's the sound cards fault. Then when you call Creative, they will blame Nvidia. Personally, I would go with a Intel motherboard and get no problems. I have a X-Fi Sound Blaster XtremeGamer with my Gigabyte P35 DS3L. It works perfectly.
If you decide to get an Intel based Mb you should really check out the 4850 or 4870 so you can CrossFire if you need more power in the future. The 4850 is more powerful in many games than the yet to be released 9800GTX+ and can be had for well under $200.