Socket 478?
AGP Video card?
Why are you water cooling this?
The money you spend on superior cooling--particularly a custom waterblock--could be better spent on more powerful computing hardware.
Each to his own I guess....
The DDC will work fine and should have lots of spare head pressure.
You could use something like, as examples, a Fusion or a Storm.
You could go for low flow resistance, as examples, an Apogee GT or a MCW-6002*.
*If you can find them. I think
lipton may still have one available. I have two and am tempted to buy a third as it is my favorite water block.
What fans were you planing on using?
That will have a larger effect more than anything else at this stage of planing.
Some information about radiator performance with different flow rate and/or fan power/speed.
http://thermal-management-testing.com/
http://www.xtremesystems.org/forums/...ad.php?t=77260
You should decide what you are willing to live with as far as noise and performance then use that to purchase your fans accordingly.