If your looking for the best mobo for that cpu just check out the am3 motherboards at newegg...choose a brand that your comfortable with that has the options you want..onboard video, full atx or micro atx, o/clocking or stock, board layout etc..
asus, gigabyte, msi, biostar,all make great boards...are you going to use ddr 2 or ddr 3..
question is very general and to make a better reccomendation need more info from you as to what you plan to do with the computer....gaming, o/clocking, stock, video encoding....also the board mentioned in the above post is a good board for stock use..ive used 2 of them in builds a year ago and both are trouble free.....but there out of production now i believe....