Pro/Forums - good idea to change my rad position?

Hey guys,

This is my first custom installed watercooling rig, so I got a couple questions. I got pretty far by now by installing/reinstalling...and reinstalling the whole thing, but I got one thing I need to get cleared up.

System :
Maze4 CPU block on Pentium IV 2.6c
Maze4 GPU block on Radeon9800pro
Maze4 chipset block on MSI NEO2-LS (865PE)
black ice extreme radiator (120x120mm) with Enermax 120mm fan

Current setup/flow : http://users.pandora.be/lapinosystem.../mod/route.JPG
Water is flowing like this :
pump (sucking from reservoir) -> rad -> cpu -> chipset -> gpu -> reservoir

http://users.pandora.be/lapinosystem...s/mod/mod3.jpg

I now have the rad installed at the bottom of the case with the fan sucking air IN from the outside through the radiator (thus also blowing cool air on the pump)

Problem is, I have too little space to install my harddisks because I rather have them at a lower position so I could fit a fan in front of them blowing cool air on them. But I cannot use the 2nd harddrive cage because of the rad/fan position

So I was thinking about placing the rad at the top of my case and let a fan blow air onto the fan from the top (or sucking away through the rad and out of the case). Got two problems with that

a) with that setup, I'll need a pretty long tube going from the pump to the rad, will this cause problems with the flow/speed of the water?

b) what is the best way to put the fan in the top-rad-situation (fan blowing air from outside into case of sucking air from rad)

All help welcome.