accualy, pump and reservoir are pretty much the same thing, AND you dont need a reservoir...
what you need to do is make something like an upside down t, sorta thingy..., what you need is
tubing
3 prong separator
pump (small pump does perfectly fine)
radiator (no... not one that produces heat)
and a CPU block (ect)
put the pump as low as posible, lower = better, it MUST be below EVERYTHING or it wont work (by everything i meen the radiator, the cpu block, and the t line.
add the water through the T line
Example of my setup ^^
oh yea, you'll need a liquid, some people go with strait water, but after a while youll have to replace your tubing due to corrosion, and if the water sprang a leek, even just a SMALL 1, your comp is fried... go with an anti corrosive anti current liquid they sell for water cooling. its the best