"So will a 1.7 ghz p-m with 1 gig of ram and 7200 rpm harddrive be faster than a 2.0 ghz p-m with 512 mb of ram and a 5400 rpm harddrive? Heck yeah, and in everything to."
I don't agree with that in such a clear cut way... HD speed, memory speed and the cpu speed affect different areas. HD speed will be nearly unrecognizable when you don't have to load / copy. I agree about the memory, 1GB of memory in the newest games can make a load of difference - I'd rather have 1GB of slower memory than 512MB of ultra fast memory. In a gaming situation the cpu is more important than the hard drive speed, but at the moment the graphics card remains a bottleneck so it isn't obvious.
On the other hand, if you have to copy large amounts of data, or hate loading screens, or play games with constant loading, you'll benefit from the fast hard drive. Ideally, of course, get the fastest of everything.
If I would *have* to pick between 1.7GHz/1GB/fast HD or 2.0/512MB/slower HD, I'd go for the former too - mostly because of the memory. But I would probably choose 2.0/1GB/slower HD over that, especially if there was a possibility of changing the graphics card in the future.