I built 3 AMD rigs and 1 Intel rig in the past year or so and AMD is definitively not a bad choice.
As for mobo, I'd look into Gigabyte or Asus (even tho both might be a little better than what you ask for). You could look at the 785G chipset or the newer 880G which both have a fairly good IGP which can play blu-ray movies (but then again it might be more than what u want).
Here is a few links:
Gigabyte 880GM-UD2H Gigabyte 785GM-US2H if you don't mind using DDR2 (I am actually using one of those)
As for the CPU, it would be useful to know what will be done on the computer in details, but I'd say any Athlon II would work unless u enlighten us with more details.