The new nvidia 7800 range is going to be coming out around in 3 more days in the uk. It will cost around 300 to 400 £ depending on the type with a GT included.
I've read in some other forums when someone posted a chinese site with benchmarking of the 7800gtx(since time difference nda was lifted so they could post it) and it was bottlenecked by a 4000+ processor, right now I don't think games need a 7800gtx the top of the line cards(1 or 2 in sli, and crossfire soon I guess) can handle current games at full res and full details.
The 7800 got 7600 in 3Dmark2005 with a AMD 64 4000+ and 8600 with a AMD FX-57.
The 6800 Ultra in a 4000+ scored 5196
The ATI X850XT in a 4000+ scored 6072
That means the 7600 only made a 25% performance gain. (in 3DMark 2005)
1. Its 7800
2. 25% can be considered a lot. I wont comment about my disgust for 3DMark and the general stupidity trail that follows it
3. Games nowadays dont have shader programs long enough to really make use of the full shader lineup ... but they'll come