The GTX560Ti 448 are priced way to close to the GTX570. They shouldn't be more than £210 or so. I would stay clear of this one.
For £240 you can get yourself a GTX570 which will perform better than the similarly priced 448 560.
Might be worth holding on just a little bit to see how AMDs new generation 7000 series perform.
Yeah Yeah I know people will say why not wait for even longer... etc etc.
But.. it'll be interesting to see how the first graphics cores built on the 28nm process technology perform esp with respect to performance /watt /temp etc. If their a bit of a dissapointment you cant go wrong with a 2GB 6950 or if you cant wait.