The smallest possible one should be the Silverstone SUGO SG05 http://www.overclockers.co.uk/showproduct.php?prodid=ca-063-sv which will fit up to a 9" 8800gtx.
Um there isn't such thing as a 9" 8800GTX... its 10.5" It won't fit in a mini-itx case, well any I've found. Certainly not the SG05/06
My personal oppinion on OCZ psu's isn't good. I found them noisy little ********, but it is a good price. Corsair are always wonderfully reliable, but come at a price.
From my understanding I wouldn't get 1600Mhz Patriots, as it isn't worth it over 12800Mhz esp when you are putting it all in a m-atx case, (Saves you a fair bit of money as well)
Other thing is the 8800GTX will be bottlenecking an otherwise top of range rig. Don't get me wrong they are wonderful cards, I've still got mine, but your building a rig to knock the pants off most applications / games for some years, and a HD4850 is faster than a 8800GTX in most things now unfortunately : (
O I just thought, if you are interested in using an AM3 chip instead, you can get a system for much cheaper.
AMD Phenom II X4 Quad Core 955 Black Edition 3.2GHz (Socket AM3) - Retail £145.98
(£126.94)
Asus M4A785TD-M Evo AMD 785G (Socket AM3) PCI-Express DDR3 Motherboard £77.99
(£67.82)
OCZ Platinum AMD Edition 4GB (2x2GB) DDR3 PC3-12800C7 1600MHz Dual Channel (OCZ3P1600LVAM4GK) £60.00
(£52.17)
With the Case, PSU and hard drive you selected added to the price, inc tax and del. I get £486.86
Good luck, less us know what you do.
http://www.overclockers.co.uk/showproduct.php?prodid=MB-201-GI&groupid=701&catid=5&subcat=1481
That's the one I'm looking at for my next build.