Here's a pic to help things along:

http://img241.imageshack.us/img241/7572/dscn0582wi7.jpg

Well, now that's out of the way :)

As you can see, the neck for the port that accepts the hose coming from the water pump, well, it came out of the radiator. Looks like it came out cleanly, but as you can see, this is a bad thing.

It'll cost ~$120 for a new radiator. I've heard that JB Weld might be able to get things up and running until I can afford a new one.

Will JB Weld be able to hold the neck into place, under a 15psi cooling system?

That would be a big NO on the JB weld.

Take it somewhere, like a radiator shop, and get it soldered/brassed back on.
That would be much cheaper.