ok, first of, the Xeon is basically an e6600 right ?? you really want you're loop to go...:: res > pump > rad > cpu > gpu > res
The order shouldn't make much difference TBH - so long as you've got the res before your pump it's all good.
if you have you're Rad after you're pump, it then takes out the heat dump from the pump aswell, which in therory should give better temps to the first block in the loop.
From your diagram its hard to work out whats the pump, whats the res and whats the rad... Doesn't really matter where the rad is in the loop tbh. As long as teh pump is after the res then just hook things up to use the least amount of tubing. Nexxo has made a few posts along similar lines iirc. Whichever way you hook up the loop, you've still got the same amount of heat going into and out of the water.
old thread but i just wanted to say i dont think 2 dual rads are necessary. i mean you are only cooling two blocks.