What socket? 939 or AM2?
What form factor? Atx or Micro Atx?
I would go for a 6150/430 board in either case. They have the best onboard graphics you could ask for along with all the features you will ever need, gb-lan, 5.1-8.1 sound, etc.
You can get a 6150/430 for under $100 shipped. They are Micro atx and they are available for both socket types.