The alternative is to get a spare router and put a specialized firmware on it so that it can log on to your other, primary, router. Then you connect your Xbox to the router with an ethernet cable.
This is what I do with two Linksys WRT54G routers. One runs the firmware called DD-WRT.
It's free if you have a spare router that is compatible and about $50 if you don't. Better than spending $100 on the MS one, though.
I use an original xbox wireless adapter. It plugs into the Ethernet port on the back and uses an AC adapter but other than that it works great. I saw them going for $40.
Originally posted by andmill11: I use an original xbox wireless adapter. It plugs into the Ethernet port on the back and uses an AC adapter but other than that it works great. I saw them going for $40.
Nice, I didn't even know there was an original xbox wireless adapter.
My recommendation is to use old Linksys wifi routers such as the WRT54G models (or similar) which can be found in abundance on eBay, sometimes quite cheaply. Flash with the awesome DD-WRT firmware and you're away.
I don't personally run my 360's wirelessly but are hooked up via ethernet between my Linksys routers. I would normally connect the routers wirelessly over WDS (all connected devices are hooked up to the routers via ethernet) but i've just changed my setup to repeater mode over 3 routers to allow wireless roaming. All devices are still ethernet connected to whichever routers but i've now added a few laptops to the mix wirelessly and roaming works great. I just personally prefer to keep as much stuff wired as i can for stability, but that's just me.
Basically with DD-WRT you just have to be extra careful that you pick the correct version for the exact model of router (obvious really) and follow the firmware flash steps to the letter. Once flashed it should be very easy to configure as a very cheap alternative gaming adapter which has way more functionality than those overprice official gaming adapters.