Need advice for external watercooling

My new project is to watercool my PC with an external setup. I think this could really help lower case temp and put a larger heatercore, so more cooling power

So here are my questions:

I was planning on replacing my hydor L30 with a more head powerfull pump, like the danner mag 3 or the mcp600 or danger den D4 12V (laing), because I think I will also watercool my x800 pro VIVO. So what is the best waterblock for the GPU that is 1/2" ID ?? And am I better putting a danner mag outside the PC, or a 12V pump inside? Room is not an issue. Also, a relay is not a problem, because the pump with always be on, because so my pc is. Finally, the heatercore I will be using is able of 2 120 mm fans in height. Will 2 120mm pulling would be enough or I'm better with 1 120mm pushing and one other 120mm pulling OR 2 120mm pushing and 2 120mm pulling (2fans or 4 fans?). Of course I would like performance cooling, but also less noise possible!

Wow that was a lot of questionning! Thanks in advance!

i built one external box for my dual setup it consisted of these parts

7 x 13 inch heater core
2 x 120 mm fans
Spiral Waterblock and Silverprop
Home made copper Y fittings to split flow to each waterblock seperate on entering and exiting
Dan Mag 3 350 gph , sealed the houseing permanent so it wouldnt leak
8 ft of line going to computer
all done in 1/2 inch tubeing

with this setup useing msi k7d master l i had tempuratures of lows 30s to low 40s under load useing two 1700+ processors at 2300mhz 1.82 volts

the only problem i had with this setup is the inconvience of moveing the computer around. if i had quick disconnects i may still have been useing it. it is currently sitting in the corner of the room

i am going to try another internal setup in the new mid tower case i just bought and hope i can still get good tempuratures with a chevette heater core and mcp600 pump along with two spiral waterblocks all in same case

Jen

http://www.xoxide.com/miposunocone.html
I use this to power a pump and 2 delta fans in my external setup. It works great and its cheap!

So as I can see Jen, 2 120mm would be enough for a p4 and a x800...i