Lapping question

[Steveiam]

Hi all first post on here please go easy on me lol. Just bought some new PC parts from ocuk :
Asus Maximus Formula
Intel Core 2 Quad Pro Q6600
OCZ 4GB (2x2GB) PC2-8000C5 1000MHz ReaperX
Asus GeForce 8800 GTS 320MB
Swiftech H20-220 Apex Ultra Watercooling Kit

I've not upgraded for a while and this is my first time using water cooling just got a couple of questions. I've seen the word "lapping" mentioned a lot now I know what it is and have done it many times at work with hydraulic pumps do I need to do it or is it something you do if you have high temps from the cpu?
Second question is a bit daft really do I use distilled or de-ironised water in the water cooling I have no idea. Many thanks for your help.

 

[Steveiam]

Many thanks for the help guys think I'll see what sort of temps I get first not sure how fast I need it I only play CS:S and COD 4 I've been playing them on a Abit N8 32X, Athlon 64 3700 ATI 850 XT 2 gig of Balistix's pc 5000 so hopefully I see a difference.