Xbox 360 as media center extender

Hello, I would like to use my Xbox 360 as a media center extender so I can watch all of the stuff on my computer hard drive on the TV.

My problem is that the computer that has all of the media on it (TV shows, movies) is not windows media center, its just XP Pro. From what I understand, you need to have a media center pc as well as the Xbox as an extender for this to work.

The folder where all of the movies are is shared across my home network right now, so I can access them from my laptop (which does have media center). So is there a way to use the 360 like another computer and just access files like I would across a normal network? Or could I somehow use the laptop as a hub to get to the files?

My other question relates to the wireless adapter for the 360. My living room is a ways away from where my computer and router are, so cat-5 is a little unwieldy. Will the wireless adapter work well enough to stream movie files over it? Most are just 700MB DVDRips, but I also have a few 720p HD movies on there. It's about 40 feet away and through two masonry walls, if that makes any difference.

If need be, I can run a cable, but I'd prefer to use the wireless if it will work. I'm mainly concerned about whether I can even use the 360 as an extender with my current setup.