I have the ASUS P5P43TD motherboard and the highest level CPU upgrade is to the Intel Pentium Dual-Core series. I woudl like to upgarde my CPU (Core 2 Quad Q8400) but not break the bank but get noticable improvemnt in processing power. Whether that's in teh Dual Core or Core 2 Quad family is ok. Whatever gets me more bang for the buck.