well, the basics are the same as the air cooling i think, in the sence that you will need a heatsink in contact with the cpu and with any other device you want to refrigerate.
so, after that you need all the tubing to connect the heatsink to a pump that will make the thermal liquid (in this case water) circulate and suck up all the heat.
so, all-in-all water cooling is expensive and the whole system needs maintenence and supervision, so that no leakages occur.
if you're planning to build a realy pumped up machine or do some major overclocking, then water cooling is probably the best way to go.
but if you're a regular user, i suggest you go with good old heatsink fans. if its noise that bothers you, there are plenty of nice silent fans out there.
hope that helped u
ttyl
