I prefer to overkill the PSU because you never know what you will need down the road.
yeah, 850 might be better though. You could still add a second 5850 and have plenty of power.
EDIT: intel build...
If there are better parts, someone please let me know, but these looked good to me.
Change CPU to i7 920 http://www.newegg.com/Product/Produc...-202-_-Product
OCZ 6GB triple channel RAM kit http://www.newegg.com/Product/Produc...-501-_-Product
ASUS P6T x58 mobo http://www.newegg.com/Product/Produc...-359-_-Product
total price is brought to $1406.
Overall, you will get nearly identical gaming performance with either build, so my opinion is go with the AMD build. You get more and faster RAM too. (though triple channel on the intel build evens it out for speed)