The PC bottleneck would be the GUI still, right? Windows, that is.
Well AMD bought ATI and is talking about moving the Graphic processor onto the chip....memory is the single biggest bottle neck at the moment ...look at what Intel has done with cache.,....half of their chips are filled with cache memory....big reason for their latest performance bump....
I think you could say right now only the gamers are slowed down by the Graphics card....I can run Beryl on a low end nVidia GE6200 PCI Express card,...it uses 3D instructions of the Video Graphics card....performs decently.
The harddrive is the bottleneck in a pc, no matter how fast and how much ram, permanent data still has to be read/written from/to much slower harddrives.