That Q6600 and any GPU card except the 4870x2, and then still would be okay, CPU temps would suffer a bit, but not much. I run an E6600, NB, and GTX 280 on my PA 120.3, temps are very fine, even in summer.
1/2" ID 3/4 OD R3603 hose by Tygon is the standard. Kinks less. The XSPC tubing is pretty nice too, not been out a long time. Buy standard worm/screw/hoseclip clamps instead of those plastic ones, they are kinda cheap and not as good as worm clamps. Lined ones are neat, a bit more but okay.
Check to see all the barbs in that kit are metal. TC rads ship with crappy plastic ones, you would want G3/8 thread, 1/2 OD fittings. Only TC rads use G3/8, all the rest of the stuff is G1/4 threads.
http://www.chilledpc.co.uk/shop/index.php?cPath=64_73
Liquid, best is distilled water, if your UK you can ask on a UK WC forums where to get it. In the US Walgreens has it on the shelf at $1 a gallon. Petras PT or PN Nuke, it's on that site. Cheap, effective, the small bottle will last through tons of redos etc, only need 1-2 drops each fill of the loop.
Look for Ian's silver killcoils too, it's a EU product, should find it somewhere. It's a piece of raw silver you put in the loop, the silver ions kill growth, like the copper ions in Petras stuff. But you only need PT Nuke OR the coils, not both.
You need no more than distilled water and a biocide. All the rest of the stuff is for poorly made loops and retail marketing hype. And stay away from dyes/additives etc. UV or colored tubing if you want color/UV glow.
Good thread: Awesome forums, wayy hardcore, great info here.
http://www.xtremesystems.org/forums/showthread.php?t=211300