The PC specifications for the upcoming new S.T.A.L.K.E.R. from developers GSC have been released on their official website; they're not apocalyptic.
The minimum and recommended list fall well within the budget of a reasonably good PC, by today's mega standards anyway. I mean, honestly, who only has 512 MB RAM now?
Minimum System Requirements
■ Intel Pentium 4 2.0 Ghz / AMD XP 2200+
■ 512 MB RAM
■ 128 MB DirectX® 8.0 compatible card / nVIDIA® GeForce™ 5700 / ATI Radeon® 9600
Recommended System Requirements
■ Intel Core 2 Duo E7400 / AMD 64 X2 5600+
■ 2 GB RAM
■ 512 MB DirectX® 9.0c compatible card / nVIDIA® GeForce™ 9800 GTX / ATI Radeon® HD 4850
S.T.A.L.K.E.R.: Call of Pripyat is being released exclusively on PC later this year.