Why do you want a 800W PSU for a GTX 460?
This setup can be run on a good a PSU like an Antec 520W Neo Eco Modular
http://www.scan.co.uk/products/520w-...x-psu-scan-exc
And just for info, the amount of Watts on a PSU is misleading. More is not always better, to judge quality have a look at the amps on the 12v rail.
For ex, a 500W PSU with 35A on the 12v Rail supplies 420W. Another is rated 600W but has 28A on the 12v rail, supplies 336W. If your setup needs only 400W at most, the 600W is out of the question, even though its rated as more watts.
A good PSU provides close to its rated Watts on the 12v rail, and has enough headroom for the 5v and 3v rails too.
CPU, GPU, HDD's, Fans are all hooked up to the 12v rail, so this is the most important part of the PSU spec.