Connecting two wireless routers (using one as a bridge)

I have a cable hookup in my room where we keep the cable modem and linksys g wireless router with WEP encryption enabled. In the living room I have an XBox 360, and a long cable connecting the xbox and the router. Sitting around I have a spare MN-500 Microsoft Wireless B router.

How do I connect the Microsoft router wirelessly to the Linksys so I can use a hardwire to connect it to the XBOX?

I'm basically trying to use the microsoft router as a wireless bridge for the xbox, and want to keep my encryption.

Thanks for the help!!
Joe Z