If you can wait until the beginning of the year, go for the quad core machines with a DX10 capable vid card.

Prices on quad core machines with DX10 cards will come down dramatically by feb. of next year.

The performance difference can be as much as 2x today's machines. I am waiting until about then for my next machine, and ofcourse VISTA with it.

Its annoying, ofcourse. Theres a few games out now (medieval total war 2, flight sim 10) that I wouldn't mind getting into, but a quad core with geforce 8800 gtx will run those games at 1600x1200 at 30+ fps, which is what I want.