3xx = g2xx with DX10.1
4xx = Fermi with DX11

most mobile parts will be based on 3xx aka G200

Now i also thing the GTX470 = 448 SU and GTX480 = 512 SU but how well can the GTX 470 do against a GTX 295/5970/5850 and 5870 @ 1ghz.

The GTX 480 may be expensive and a bit point less but i think the GTX 470 maybe a great buy lets see how it goes.