There is flow rate, and head pressure. The more restriction you have in your loop the higher head pressure you need. The MCP35X is a strong pump with nice flow and even better head pressure, but don't take my word; research it. Always research before you buy.
Some good places are http://martinsliquidlab.org/
Both of those sights can be found in the sticky at the top of the forum. If you havn't read it you should, it has lots of useful links and info on the exact question you are asking and everything else involved with watercooling.