See attachment picture for a visual reference.

I have a Base Station or router (Point A in picture). Then i have computers B and C which I want to be connected to the router (and hence the network). But as you can see from the picture computer C is out of range of the router. However computer B is in range of the router and in range of computer C. So I'm curious if its possible to set up a computer as a repeater, but not just a repeater.

Ideally i would want the computer to be able to receive information intended for that machine and then repeat or "pass on" the information that isn't meant for that computer.

The "computers" will be custom built by my friend, (they'll be more like small embedded systems running Linux), so i guess another question is, what would it require (hardware and software wise?)?. Two WiFi controllers (eg: apmcomm–Wireless, GPS, Bluetooth, WiFi, WLan, IPD, SiP, Combo, modules, Wimax, RF, TMC, RDS-TMC) ? From what I've read it would need certain/modified firmware...

Any comments, good readings?

Thanks