if its for gaming, you'll really want to get an athlon 64 since their superior in nearly every way except encoding/decoding (i'm not being biased at all), but since you want intel, you'll want at least a 2.8C cpu, meaning a 2.8GHz cpu based on the northwood core, NOT PRESCOTT! if you want to overclock, you'll be able to get at least 3.5GHz out of it, which is pretty nice. also, tell us how much you plan on spending total for the cpu/mobo/ram upgrade. it'll make it much easier for us to put something together for you.