Graphics card wise I would go for the 8800 GTS 512MB over the GTX not a huge difference in performance but still a ~15% price differential.
If you want even more graphics power you have a couple of options and they are, first the HD 3870 X2 from scan will cost you £270 currently the fastest thing around but you have to be aware that it is efectively 2 HD 3870s in crossfire on a single card. The second option would be to crossfire 2 3870s or SLI 2 8800 GT but you would obviously need a different motherboard for SLI.
On the whole single card solutions offer more predicitable performance so I would probably go with the 8800 GTS but if you want the fastest of the fast then the the HD3870 X2 is the way to go