Dual core is not the same as dual processor. For those just joining our viewing audience, dual core means two processing units on the same chip. Not to be confused with HyperThreading, which is one core with two logic paths (threads).
Intel 840 = you need the new 955 chipset mother boards, they wont work on 925 or 915 chipsets, are better at some video rendering, and suck at games because the cores talk to each other through the frontside bus ( one web site benchmarked the 3.6GHZ 840 as equal in doom 3 as a 2.8 northwood core! )
AMD X2 4800 = no new motherboard! all 939 motherboards will support it with a bios flash. The cores talk to each other, the memory controller, and the HT link through the same crossbar on the chip package. Really low latency in this method! They beat the 840 in most benchmarks, and are only a couple frames slower in games than their single core version ( X2 4800 is same thing as 4000, just with a second core ). The only benefit to the Intels are the price. A X2 4800 will be over a grand retail ( USD ).
I would suggest any fast 939 board. Then wait for the X2 4200 to come out. That one should be about $500. Just make sure to get low latency memory (2-2-2-T1) and you\'ll have enough CPU game power in that setup for anything but 6800 Ultra SLI
Hope I helped ya.
