reply to NullQwerty
Re: Water Shut Off Valve Not Shutting Off Fully Nah. It's a bit of a pain in the ass to have your ass-crack up in the air while under a sink and bent in positions that the human body wasn't meant to be in, but the wife or GF will get a kick out of your manliness as you are under the sink.
When one goes, it's best to do them all in the house. This way you know you did them all at the same time and know you won't have an issue again till your an old man. Plus it's something simple you should learn to do instead of running out and buying a whole new valve. Few dollars only for the whole house (and maybe the taps outside for your hose). Plus once you do one then the second one is easier and you will be happy you did it.
Then once it's all done, you suck in the gut, flex, and say, "honey I did it, I deserve 3 beer". Then at work Monday you find out she took a pic and put your plumbers crack on facebook...
Then you get to help someone else here by telling them your war story a year from now.