I build systems based on performance and capabilities.
in the last 3 years since Core 2 cam out and now the I7, AMD is hard pressed to have a processor that can compare in performance in both gaming and business.
the I7 Architecture is revolutionary, and removes the need for FSB based processing, and as such, the results are the Core 2 Quad (4 CPU) and the I7 Duo (2 CPU) running at 3.2 Ghz each, the I7 blows the doors off the Core 2 Quad.
Amd has nothing on the market currently that can match the I7.. the only thing about the I7 is the cost at the moment.. Motherboard, DDR3 Ram and the I7 processor is still a bit expensive compared to Core 2 or AMD equivalent
Then with the I7, if you want Overclocking.. you have the Intel 960 chipset.. and for ultimate speed.. get 2 HDDs at 10,000 RPM for say 1 TB total storage at 6 GB/s transfer rate and set them up in Raid 0 Striped. (equivalent of 12 GB/s. combine that with 16 GB DDR3 or more system memory (fastest rated FSB available, though the system doesn't use FSB, the memory can keep up with the I7 transfer rate) with a 16 GB USB stick set in Ready Boost on Windows 7, and for gaming, throw in 2 NVidia 295 GTX OC2s into SLI (or even 3 or 4).
That would be a decent machine by today's standards.. but it is cost preventative..