If you're looking for simply the best Dolphin PC, the GPU is overkill. For CPU, you just need two cores running as fast as bloody possible. I don't know for certain how well the i7 750 overclocks but get the CPU in your budget that overclocks best. The 750 probably isn't a bad option.
The reason is, Dolphin does MOST of the work on the CPU and can only utilize two CPU cores (no, multithreading beyond two cores will NOT be available in the future). As much stuff as possible is already offloaded to the GPU but it's not much so you don't need a very powerful GPU for Dolphin.
So, in conclusion, two key things to remember:
CPU: Core 2 or Core i5/i7 line (or its AMD equivalent) overclocked to the max.
GPU: A 9600GT (or its ATI equivalent) or better.
The reason is, Dolphin does MOST of the work on the CPU and can only utilize two CPU cores (no, multithreading beyond two cores will NOT be available in the future). As much stuff as possible is already offloaded to the GPU but it's not much so you don't need a very powerful GPU for Dolphin.
So, in conclusion, two key things to remember:
CPU: Core 2 or Core i5/i7 line (or its AMD equivalent) overclocked to the max.
GPU: A 9600GT (or its ATI equivalent) or better.
Windows 7 RC Build 7100 x64 || Windows Vista SP2 x64
Intel Core 2 Duo E8500 (3.16Ghz)
ATI Radeon HD 4870 512MB (750Mhz/900Mhz)
OCZ Vista Gold 4GB RAM (2x2GB) DDR2-800
Asus P5QL-E
OCZ GameXStream 600W
Intel Core 2 Duo E8500 (3.16Ghz)
ATI Radeon HD 4870 512MB (750Mhz/900Mhz)
OCZ Vista Gold 4GB RAM (2x2GB) DDR2-800
Asus P5QL-E
OCZ GameXStream 600W