All of these questions are answered in the sticky at the top of the forum.
Google is the best source to help answer questions.
Sorry, but this question is asked about 10x a week here (and this is pretty much a noob forum for watercooling...a handful of us have any idea.) Please read a little before asking questions...this is the first rule of any forum...anywhere on the web.
Please read the forum threads below and as much as you can that is linked within. Being an informed consumer will only help you in the long run when it comes to spending the couple hundred bucks.
What is your budget? What are you wanting to cool?http://www.overclock.net/water-cooling/226970-water-cooling-essential-threads.htmlhttp://www.tomshardware.com/forum/256607-29-watercooling-read-first