This is my current machine - by no means a top end spec.
(About 9 Months Old)

Intel Core2Duo 2.2Ghz
Radeon X1950 512MB
2GB DDR2 800mhz Memory

This runs MTW2 fine, with most settings maxed at 1280 x 1024 res.
I would imagine that the new game should run OK with these sorts of specs, and by the time it's released, you will be able to pick something like this up for very little.