One pump enough?

I've been thinking about diving head first into water cooling for some time now. I'm finally going to pull the trigger soon and have been planning out a system. Basically I'm wanting to get the basic loop set up and allow for future upgrades to my current system as well as add a little more overclocking headroom. This is what I'll be keeping from my current system...

Gigabyte GA-990FXA-UD3 V1.0
Phen. II X3 720 Black Ed. (this will be upgraded soon along with GPU, probably after the first of the year)
ASUS HD4870 DK TOP 512MB (runs a little warm in my P182 even with a front fan blowing directly on it)
Corsair VX550W
OCZ Vertex 3 120GB
3x standard 3.5 sata HDD (probably only take one with, but depends on space.)
2x DVD/RW drives (may keep one, depending on space again.)

I am going to pick up a new case to "showcase" my cooling setup. Debating on the Corsair 800D or Xigmatek Elysium. Currently I'm leaning more towards the Elysium as it's a bit cheaper, bigger, and a bit more adaptable.

My main uncertainty is whether or not a single pump will handle what I'm considering. The loop I'm planning as of now is res/pump/3x120 rad/cpu/1x120 rad/GPU/res. I'm looking at the XSPC EX line for both rads and a Phobya DC-12 400 pump (jingway type) with the XSPC raystorm cpu block and XSPC rasa GPU block.

Basically my idea with that loop is that the 1x120 rad will provide a slight boost to the cooling of the GPU. Is there any logic in this or am I over thinking it! (I tend to do that with most things) And if my logic is sound, will the Phobya pump provide adequate flow/head pressure to efficiently handle the loop?

BTW, I'm looking at the Koolance FAN-12025HBK (2600RPM, ~100CFM, 33dBA, 5.4mm static pressure) for the rads. Most likely to a push pull on the 1x120 and push configuration on the 3x120, initially anyway. May eventually add a speed controller if the noise becomes too much.

Thanks for any help, ideas, or suggestions.