What are you using to convert your .CR2s? If you are using the Canon software, it is a known fact that the Mac version of the Canon software is slower than the PC version. They have not optimized it. Why not try another raw convertor. Try the new public beta of LightRoom. It is very fast, and for now, it is free. And I think the converter in Lightroom is the new standard for convertors. The convertor in PSCS2 is likewise, very fast and flexibile. Also, Photoshop Elements 3 uses the same convertor as CS2.
Frankly, as with any new technology, there will be growing pains with the new Intel boxes. For early adopters, maybe some of the things they will have to go through will be acceptable to them. But if you are easily frustrated with small problems, then you are much better off with current technology that is tested and stable and has tons of software available that runs natively on the 64 bit processor included. I think many of the claims for the new Intel processor architecture are inflated and referr to "as much as" twice as fast. I suspect that you might see significant improvements from the video card, but I don't expect that you would see a large improvement in general processing speed. Don't get caught in the Steve Jobs reality distortion field. Enjoy your computer. OSX is still the best operating system under the sun.