Well - I just build myself a new computer a few months ago. It was not a dramatic update (recession is noticeable over here), but merely a "shift" update (my music computer running Cubase etc. "got" the somewhat older hardware, while my main computer was build new).
My main computer now has the following parts:
i5-3570 ( 4 cores at 3.4 GHz ) with Gelid Tranquillo Rev.2 cooler
2 x 4Gb-1600 (pair kit). Making 8Gb total memory.
GeForce GTX660 with 2Gb memory (MSI twin Frozr III).
1 x 1Tb and 1x 750Gb at 7200rpm hard disks
Antec One case with (replaced) silent Case fans
Cooler master Silent Pro 600W power supply.
MSI B75MA-E33 but that one will be replaced by a ASUS P8H77-V LE (because I wanted more PCI slots).
It is a real silent system. I hate noisy computers, so I am prepared to pay a little more for noise reduction (although some noise reduction does not have to be expensive - take the Gelid cooler as an example).
So - I think I can run X Rebirth at a somewhat decent speed...