i think you would be best off to make a chain
pump -> video or chip block first (it is cooler than the cpu and wont raise your water temp much versus the cpu making warm water go to the video or chip block) then cpu onto the -> Radiator and back to pump (look into a chiller block just before the pump)
here is the web address:
I would think that you'd want the radiator between the pump and everything else....
1) so that you get rid of the heat that the pump adds to the coolant
2) get the coolant as cool as possible just before you apply it to the heat producing elements. I think the t-junction idea is actually a pretty good one, just put it right after the radiator. With that there, you don't introduce heat into the coolant for either of the chips. Then you'd just have to tee it again just before the pump...or put an extra inlet into your resevoir (boy can I not spell or what?) depending on how you have yours set up.