Regarding cold water, I've heard exactly what baffled has. Drinking it cold does make you burn more calories.... by a tiny tiny bit. If you don't like it cold, you might burn more drinking it at room temp and then doing a few jumping jacks!
As for drinking in general, I just don't worry overly much about my water intake per se, and I haven't found it to be a problem. I'm not saying I don't drink it, just that I don't pay attention to it.
