I have this board, and as far as I understand it, you can use a SINGLE Athlon XP, Duron, or Thunderbird in it. If you want to take advantage of the mult-processing however, you have to use Athlon MPs. I have 2 Athlon MP 2000+ running in mine. I'm still struggling to get all my peripherals to work in it though. I think MSI has some updating to do yet before it is really ready for prime-time!