For those wondering, I do believe that the latest builds of PCSX2 do seem to be better on quad core processors than on dual cores. When I play on my i7, I noticed it doesn't hit the HT threads at all but it does spread the CPU activity across all 4 cores. This is with the SSE 4.1 build, so your mileage may vary.
As far as I read its Dual Core only on the forums. A lot of time spent reading their forums also revealed that you really need a 3.5-4Ghz i5/i7 to get full speed basically anything. 4 Gigs of Ram is fine, and anything above a 8800gt is also fine...but its really the CPU that matters the absolute most. As for now, for me, I'll hold off. Maybe I'll revisit sometime next year if I have a faster system.