well, the very best tubing is copper pipe, and is ONLY available at the hardware store. You'll need a few fairly inexpensive tools though. namely a pipe cutter and pipe bender. You can also get the super soft hand bendable stuff, but it;s hard to get it straight and pretty.
The stuff requires it;s own compression fittings, but they are available at the hardware store too. You can get either a pipe bending tool, or a spring pipe bender. the tool will bend to specific angles and looks like a weird pair of pliers where the pipe bending spring is an hourglass shaped spring you put around the tube while you use your hands to bend it which keeps it from kinking. Lower cost, less accuracy, more elbow grease required.
Easiest thing to do is find out the thread count and diameter of your radiator and block connection points, then go to the store, find the plumbing guy, and get him to hook you up.
if you have barbette connectors (look like toy christmas trees) you will need plastic tubing, but, again, the diameter of the barbette is all you need. They will likely sell several types of tubing by the foot that you can use. Just make sure the tubing is temperature and gas resistant. some plastic tube is permeable to air but not water, and you want to keep air out of the loop.
IMHO specialized watercooling tube is idiocy. Even the copper stuff will probably cost less than the watercooling tubing, even if you buy the chromed stuff.
Edited by bombastinator - 10/24/13 at 10:54am