I've got an Athlon 1800, GF3 ti500 and 512mb, and it runs just fine. People seem to be under the impression that they can run every game at 1600x1200 with 4x AA and all the other bells and whistles - Be realistic. I run in 800x600x32, and it looks great.
Stop being elitest, and use some sensible options - Perhaps then you'll get a decent frame rate, and won't keep bitching about the developers.
For the record, the game is more arcade-y than the others in the series (which i've loved), but i still really like this. I think the helicopter is a little much, but perhaps they'll be an option to turn it off or lower the frequency of barrels. A future patch may also solve some of the problems.
Definitely going to buy it when it's released