I must admit, I'm more than a little confused about the tech issue here.

A Router needs a net connection, most are modems in their own right, but even then I don't think you can have two modems connected and working on one line.

Sounds like you need a router for the desktop anyway, and that will come with wireless as standard, allowing you to surf the net.

Here's the thing though:

You shouldn't be stealing and you shouldn't be going behind your parents' backs. If you're being punished for something, then I think you should suck it up and earn their trust, not try to get around them. Fact is, you don't need to play computer games, it won't kill you not to. Hell, at the start of this year I had no net for about 2 months, I lived.

Alternatively, if you've been banned for practical reasons it's probably because your Dad found something on the PC that shouldn't have been there and traced it back to you.