not nice at all....
you have an i7 on socket 1366 for sure (with 6x2GB of memory, which runs in triple-channel mode) with a TDP of 140Watts (thus enabling a nice automated Turbo-overclock when running single- or dual threaded apps).
Apple blatantly charges $200 for the "upgrade" from i5 750 to i7 860, which is still s1156 thus runs with dual channel DDR3, while the actual price difference between the 2 cpu's is about $90 if bought by the 1000's.
If you REALLY know why you REALLY need a Mac and it's time for a new one, by all means, take the i5 iMac, it'll calculate everything you want faster than you can imagine.
In ALL other cases, please stay away from that machinery and buy yourselves a PC that fits your needs, for half the price or less.