Check the ASUS website for your motherboard model, and then look for the supported CPUs.
That's what we will do anyway so it's better if you start learning how to do it.
Looking at the CPU support list for you mobo Im afraid its bad news. The highest spec chip you will be able to use (if you can find one) is P4 - 672 3.8 ghz, but its still only a single core cpu.