Dom's pages, above, are the only place you really need to go to learn everything about kefir.
I first started out with water kefir. It made me feel great!... but it'd give me pounding headaches the next day. After a bunch of research, I learned it produces a tiny amount of methenol (not enough to poison you :)... but I guess I'm just very sensitive to it.
I switched to the milk kefir after that.
