the e2180 will bottleneck anything 9600GT and up. fact. e5200's can easily hit 3.0GHz (well they usually do... my mobo is retarded, but it appears to be stable 240x12.5 now!) and imo is much better price/performance. if you bought a 4670/4830/4850 now, you could then CF it later on... except its a G31 :lol:
my recommendation for the lowest possible price (and i dont recommend it at all, i mean my build was budget and its playing crysis on max...) is some retarded e2xxx, a G31 and some cheap graphics card.
what i would really recommend though, is at the very least a P35, but a p43/45 would be better, an e5200 and a 4830 (for the moment, later you can CF it with a 4850 or 4870...).