Don't use vodka.. That's not a good idea..
There are a ton of different liquids you can use. Most people use a mix though, as the pre-mixed solutions are like $30 a bottle. IMO, that's a little much. Distilled water is best, no mineral build ups that way. You can mix that with some anti-freeze, pre-mixed solution, there are all kinds of different ways you can go. Right now I'm using distilled water and anti-freeze, with dye. I had some PC-tonic (pre-mixed) but I ran out.
You have to watch out for build ups. And when you mix metals in your loop (brass, copper,etc) you really have to watch out more for it. But basically, you can use straight distilled water, with a little bit of some kind of biocide/anti-freeze stuff.
As far as tubing, that's really up to you. There are some "name brands" that don't kink as easy, or have some kind of color. But I just picked up 15' of clear tubing from lowe's, and got some anti-kink coils. It adds the look I wanted, and prevents kinks.
You can spring for the name brand stuff, but it's more expensive, and really besides the kinks thing, offers nothing different.
Here's a couple of the best stores for H20 gear:
Jab-tech Petra's Tech Shop Danger*Den Performance-PCs.com, ... sleeve it and they will come Sidewinder Computers - Supplier of High Quality PC Modding and Cooling parts FrozenCPU.com | 1.877.243.8266 | World's Largest Selection of PC Modification Supplies PC Mods, Case Mods, PC Cooling, Gaming, and More - Crazy PC
Here's a link to pics of my system, so you can see what I'm talking about with the anti-kink coils.
http://i99.photobucket.com/albums/l3...d/P1020010.jpg http://i99.photobucket.com/albums/l3...d/P1010994.jpg