Airport Help?

Basically my problem, is that I have a game room that I just set up with my PS3, but this room, is separated from my router by a lot of walls, so the connection to online play on the PS3 is really crappy. What I was wondering, is if it would be possible to buy a new airport extreme/express, and create a new network entirely on that. If this is possible, what do I need to do to get a new network up and running. Another question I have is if the airport express can have guest accounts running on it. The reason I want this, is because I want to use games online with my DSi, which only has WEP supported wireless access, and I would rather use the more secure WPA2 for my PS3, without having to change the security type every time I used my DS. Thanks for any help provided!

What are you using for wifi currently? If it is an apple router you can get another apple router to extend the network. If it is something else your best bet is to get the same kind of router to extend the network. An Airport Express can run as a network extender but it only extends Apple networks. If you could wire it in - closer to your game room - you could set up a completely different network.

I went a different route and used powerline networking from netgear
High Performance Powerline
This allowed me to use a media center PC to stream movies to my xbox - every wireless solution I tried didn't have enough bandwidth - or the QOS was so bad that it stuttered.

Another choice for your dsi - is a usb adapter that can hook into a computer.
nintendo dsi wifi usb connector - Google Search
I just didn't like running a full wifi network with WEP encryption - seemed like a waste.