I've been trying recently to connect a wired LAN printer and my Xbox 360 to the wireless LAN in our house. This proved trickier than I expected.
First off I wanted to connect my old Linksys WRT54GS v2 wireless access point to the existing wireless network, so that I could hook my printer up to it. The wireless network is using WPA-PSK authentication. I reflash the WRT54GS with OpenWrt, version 8.09 RC1. I didn't find OpenWrt very friendly, but I managed to get it to join the wireless network. Unfortunately there seemed to be some problem with bridging -- the wired and wireless networks were not connected.
Eventually I gave up and switched to DD-WRT, which worked much better. I set it up into Client Bridged mode, and it just worked.
The next task was to connect my Xbox 360 to the wireless network. I bought the wireless adapter, but I found it would not connect to my wireless router, a Linksys WAG325N. Apparently this is a known issue. The recommended fix is to downgrade to version 1.00.06 of the firmware, which unfortunately did not work for me. I upgraded the router to the latest firmware, v1.00.12, and made sure my Xbox had the latest updates. Still no joy.
I read reports that the Xbox 360 worked fine with the WRT54GS, so I wondered if I could create a second wireless network just for my Xbox. Fortunately I discovered that DD-WRT has a repeater mode and a repeater bridge mode. In repeater bridge mode, you create a virtual wireless network with a new SSID, and then traffic is bridged between the real wireless network and your new "virtual" wireless network. The virtual wireless network is a real wireless network to all intents and purposes.
After some poking around the DD-WRT GUI, I had it all configured and it works! (Note: I skipped the nvram set wl_ssid="" step -- you don't need that for Repeater Bridged mode.) The path for traffic from my Xbox to the internet is now something like this:
Xbox <--> WLAN 2 <--> WRT54GS Access-Point <--> WLAN 1 <--> WAG325N router <--> internet
DD-WRT is pretty sweet. I've only scratched the surface of its features.