Core 2 Duo: High performance DUAL core Desktop CPU (e.g. E4300, E4400, E4500, E6300, E6320, E6400, E6420, E6600, E6650, E6700, E6750) Core 2 Extreme: Ultra performance DUAL core Desktop CPU (e.g. X6800, X6900) Core 2 Quad: High performance QUAD core Desktop CPU (e.g. Q6600) Core 2 Quad Extreme: Ultra performance QUAD core Desktop CPU (e.g. QX6700, QX6800, QX6850)
The Quad extreme (QX6700, QX6800, QX6850) will, the normal Extreme (X6800, X6900) won't. Basically if you want a quad core, look for the Q.
Ok, I read this somewhere but I cant remember, so bare with me. I heard that a Core 2 Quad is just 2 duel core processors compacted into 1 cpu, while a Core 2 Exteme (QX____) is a "real" quad core, which is 4 seperate cores. Btw, that's the one that costs $1000USD, while the Core 2 quad only costs 279 I think.