Anyone know if, and what, socket is used for the iMac? Is it the standard 479 or is the processor soldered in or otherwise very complex to replace?

I'm considering paying the extra 160 for the 2.8GHz Core 2 Extreme in the next four weeks but if I can drop in a quad 3GHz processor in 18-24mths time for 200 or so, then that would be preferable.

Or am I being too hopeful and Apple's use of the Merom and Merom Extreme going to be too limiting in this respect?

Thanks for any insight.