Andy, as the resident video game geek, I figure they'll revoke my membership card if I don't chip in... Let me ask some questions:

* This is for an XBOX 360, right?
* You have a wireless network in your house already, right?

Assuming both are yes, you are looking at $60-$90 for the adapters -- they're readily available online... Microsoft makes one, as does Mad Catz... FWIW, I think these prices are highway robbery for a WiFi adapter.

But in truth, I'd run the wire man... Even if you have to do an overland wire temporarily before you can in-wall it. I think you'll have better results, lower latency, less problems if you go wired. Plus you'll save money.

If you need help/tools/etc for making Ethernet cables, I've got everything you need. I'd presume you are dialed here, but ask if not.