I've simply added a solid black border to the edges to keep the images within view of TVs that cut off the edges.

I can't suggest much more than what Tony has, I just figured I'd throw out the technical terms for this. There are two areas you need to be concerned with, called "safe action", and "safe title". In broadcast, any sort of text you want in the screen needs to be within safe title, to guarantee that it's on screen. Anything that you want on screen, but it doesn't matter quite so much if it gets cut off or distorted a bit (i.e. most TVs will show it), needs to be contained within safe action. Everything outside that better not matter too much, because it'll likely be cut out.

See here for more info, and some templates showing you just where the safe action and title zones are.

Edit: On second thought, rather than just going mad with the clone tool, I'd suggest using a few layers with the image mirrored in X, and a few layers with the image mirrored in the Y. Move those layers so they line up to extend the image out to dimensions you want. Then you can bust out the clone tool to break up the symmetry of the mirroring, and get rid of the white lines from the image edges. The toughest part is the left side, where you have to paint in some bushes and fence. The other side is just building, and shouldn't be too hard. On a whim, I painted up a 720x486 version using this method, and it worked pretty well. I saved it as a tif, so it's too big to attach -- if you want it as a jumping off point for a larger version, let me know.