HD respone, read, and write are the bottleneck in most systems.
I think people over estimate what they need.
Like 8GB ram, cmon few people will actually use that if the whole market is considered.
I get by on 2GB just fine, and i wish i spent more on a GFX card than on my quad core, which really, i dont need.
Core 2 Duo (8400), 2GB PC6400, p35/p45, 9800 gt / gtx 260 is all you need.
and spend the extra dough on some SSDs if you really want to see a boost in performance.