PC gamer already did a cost comparison (using some speculation).

Originally Posted by tomasp3n
Upgrade? Well, I "only" have a quad core, but the RAM is not a problem. And my rig is about 4-5 years old. the graphics card is just a year old though, and I have no problem running any game at high settings so far.

I think I will actually buy a PS4 though, i skipped the last generation.

I'm at 4GB RAM and by motherboard is DDR2 (the reason why I haven't upgraded it). It was my plan to upgrade the board and memory this year though. The new consoles have nothing to do with it.