[chrismorse]

With two pipes coming out of the going I'd assume one was the feed and the other taking water out to another point. I'm guessing the line with the plastic valve is going out and you might be able to shut off that run of pipe if not needed. I'd do as Dad911 suggested and blow the water out to prevent freeze damage.
From the second photo, it looks like there might be a crack in the valve at the top. If you are going to replace the valve, i'd recommend using a brass full flow "ball" valve.
Might be worthwhile to insulate the exposed pipes under pressure.
good luck,chris