first off let me say nice case selection
For my last xeon setup I wanted that Chenbro but ended up getting a cheap Intel 5U case for 40$ delivered, same size but not compartmentalized (sp? :shrug: ) like yours is, quite nicely too.
I hacked at my 5U case soooo many times trying to figure out the best way to mount a double rad. I have to shoot down psychofunk's idea because I sort of tried that already. I had a double exhausting up top and tried a BIX infront. Either way you do it the air going over one radiator is also going over the other. Really did nothing for my temps and just added TONS of clutter.
Putting the rad infront of those two 120s would be easiest for your case, but if you have time and like hacking stuff up Id go another way
Take out those two HDs you have and put them under your CDROM, seal off that top part as much as you can so your PSU pulls air over your HDDs only.
Then hack out HDD cages as much as possible so you can just put a double 120 HC right there in the front right by the bezel. Having those two 120s suck through the HC/radiator would be more efficient than blowing through them, more fins would get airflow. That would give you like a 5 inch plenum, or however deep those HD compartments are. Just seal up as much as you can so the only place your 120s can pull air from is through the rad. having that plenum and not having the fans RIGHT on the rad will keep the noise down also. Id cut out those grills over the 120s too, just adding air restriction.
To give you a general idea:
As for pump Id definitely say mcp600, maybe even two if you arent strapped for cash. Two mcp350s would be a waste. You arent low on space so not really any reason to go for them...
A MCW6002 because of price and performance, and two maze4 GPU blocks because of low pressure drop, performance, and price. NB block maze4 also, lowest pressure drop but not really priced well =\