Here are the details:
http://www.techpowerup.com/117902/XF..._Pictured.html
http://www.techpowerup.com/117897/Ge...s_Surface.html
http://www.fudzilla.com/content/view/18145/1/
£299 and £429 rrp in the UK? I make that £4 per extra shader in the 480 model :D