Yeah stay away from Intel people. I bought an Intel once and it had to be slower then macs. It was a p4 2.8Ghz but i've seen p2 processors do better with no overclocking. I couldn't play CS:S on low settings cause the cpu lagged.
I don't have any complaints for the amd's i have cause they own of course.
I don't notice any difference from ddr and ddr2 though.
Oh and xfx geforce 6800 xtreme and EVGA geforce 7600gt are basically the same but the 7600gt is a tad better with the graphics. Not very noticeable.