Connecting two ethernet cables into one computer?

[tracker]

Here is what I want to do:

I have a new computer. I'd like to use my old computer as a render farm for Autodesk Maya 2008. I only have one ethernet port on the new computer. I can hook up the two computers using an ethernet crossover cable. I tried it out and it works. However, there's not another ethernet port, so I can't have internet while the two computers are hooked together. It's also a pain to hook and unhook the cable because of the computers' location.

Is there a way to hook the old computer via crossover cable and my internet ethernet cable into my new machine? I know they have LAN switches, but I don't know if this would work or if it is what I would need? If a LAN switch would work, is there anything special I'd have to do to get it to recognize both networks (i.e. the router network, and the local network)?

10 points for the best answer
See the thing is, I don't have any room near the router for another computer, and I didn't want to have to buy another network card, or another 100ft ethernet cable to reach the router. The computers can be on the same network, it's just I have a 3ft crossover cable already and thought that might be easy, if only there's some way to get it hooked into the new computer along with the internet line.