Ok that isnt a problem there are plenty of AM3 boards that use DDR2 memory.
ASRock A785GXH/128M AM3/AM2+/AM2 AMD 785G 69.99http://www.newegg.com/Product/Product.aspx?Item=N82E16813157180
This is a great board and can handle up to 16GB you really cant go any cheaper then this board. Any board cheaper then this the ram maxs out at 4 GB. And it also has crossfire support if you want to maybe run dual GPUs one day.