For "AHII" he likes Duals, most other games make use of the Quads and higher end graphics cards. If all your going to do is AHII and nothing else sure get a Dual. Also the specs he quoted from me is a system I had built out not for aces high alone but other games too and was for sale at over 200 less then newegg pricing.
Actually, Aces High II is one of the few natively multi-threaded games on the market. Most games claiming to be multi-threaded actually are leaning on the asynchronous nature of DirectX.
The reason dual-cores are preferred is due to the normally higher clock rates, which yeild higher raw performance levels than a quad core. On a clock matched quad core to dual core, there is just not enough "bang-for-the-buck" in a quad core to warrant the cost, unless you are into heavy movie editing. Both Sony Vegas and Adobe Premier will make use of all available cores and they have the ability to actually saturate all the cores available.
Quad cores also use double the power of a dual core, and require far more of the HSF due to the heat they can generate.
As far as my current computer goes, I never have been a "bleeding edge" kind of guy as I depend on computers too much for the work I do. They always have to work and work flawlessly. I am conseravtive, and shoot for a good performance value. If you want the absolute bestest, fastest, highest endest computer, I am not the guy to talk to.
Right now, the CPU is at 3.75Ghz, with an FSB of 533Mhz, running one to one ratio, with the CPU and the peripheral bus strapped to 400Mhz. It runs cool, and more importantly, very quiet. I am happy with the performance. It boots before the "kitt" eyeball makes one full pass at the Windows boot screen. I love that. Very stable and cool running. Video encoding has been just fun to watch now, it is so freaking fast.