Xbox Live via a bridged connection?

[Stigmata]

Here's the situation.

My wireless router is on the main floor. The gaming TV is in the next room, with my Xbox 360 and Wii. My PC is upstairs in my bedroom. The Xbox connects to the router via LAN cable (not long enough to reach my room), and my PC connects to the router via wifi. I have the Xbox 360 VGA cable, which allows me to play in HD on my computer monitor.

What I want to do is connect my Xbox 360 to my PC via a LAN cable, bridge my LAN and WAN connections, and use that bridged connection to allow my Xbox 360 to connect to Xbox Live. This means I wouldn't have to buy either a super-long LAN cable or the hundred-dollar Xbox 360 wireless adapter in order to play multiplayer on my computer monitor.

I haven't been able to locate any guides that ended up working for me. Does anyone know any way to do this properly?

Router: Linksys WRT54GL w/ custom firmware (DD-WRT)
Wireless card: Linksys WMP54GS

 

[giant384]

go into your network connections
select your wireless connection and lan connection by holding ctrl
then right click on either of them then press bridge connection