what kind of processor are we talking?
AMD -> out of luck
Intel 478: try to get one of the few mATX still featuring this socket.
1. 2GB RAM
2. Mobo with PCIe x16 slot and 2 / 4 DDR2 RAM Banks
3. GF 8400 - 8600 GTS depending on your remaining money
The lower end HD2300-2600 GPU (NOT THE HD2000!!) are an option as well.
All of those have HD video decoders and feature DX10 / unified shaders
AMD -> out of luck
Intel 478: try to get one of the few mATX still featuring this socket.
1. 2GB RAM
2. Mobo with PCIe x16 slot and 2 / 4 DDR2 RAM Banks
3. GF 8400 - 8600 GTS depending on your remaining money
The lower end HD2300-2600 GPU (NOT THE HD2000!!) are an option as well.
All of those have HD video decoders and feature DX10 / unified shaders