Get an nVidia GTX 285 video card. That's the cheapest one that will provide the most compatible acceleration with Adobe's products.
What ever processing is not picked up by the GPU, which is still quite a lot, will fall on the CPU. So if you don't like waiting for filters to run upgrade the CPU. If you're patient keep the stock model.
RAM will allow you to have more, larger files open at one time before starting to swap to the to hard disk. When you're swapping you'll hit about a 1000x speed penalty. So make sure you have enough RAM. 6 GB should be enough, 12 is definitely enough. (32 GB is insane, and anyone who puts that much in a home machine shouldn't be trusted.)
