The problem: I had a wire running from my main router to my living room. I was afraid my kid was going to trip over it, and I was dreading having to run the wire along the roof cleanly. So I started asking around to see how I could get a secondary router to act as an access point (act as a receiver and pick up a wifi connection) and then distribute hard wired connections to my Blu-ray player, Xbox 360, Xbox, and Laptop which is hooked up to my TV.
The solution: DD-WRT, an alternative firmware (hack) for your router will take care of this for you. In this case I hacked a Linksys WRT54g v 6.
Step 1: Download files for your supported router here.
Step 2: Flash your router, see instructions here (specific to WRT54G). If you have a different router when you search using the link in Step 1 (above) it will give you directions specific to your router.
Step 3: Adjust Settings to get Router to act as a Client Bridge. See here:
To test the performance I had a blu-ray HD movie streaming from Netflix, while streaming a movie from my home PC using XBMC on the original Xbox, and using the Xbox360 to play NBA Live 10 online. I was surprised to see that everything was functioning without a hiccup. I even used Tversity (which acts as windows media center server on XP) to stream videos to my xbox 360 from my home PC.
Another benefit of doing this is extending your wifis reach throughout your home. Most people use DDRT for that reason.