Connection help!!!!!!

hi, i have a bt voyager 2100 wireless adsl router.
i have connected it to my computer through a rj-45 wire and i have configured it and the internet works fine. So then i got a wireless pci slot for my other computer and it never worked because 'the device cannot start'. So i bought another and it stiill diddnt work, so i bought another by a different brand but it still didnt work. so now i bought a usb one and it works !
it connected but the signal strenght is **** and on the computer with the usb it wont connect to the internet!!!
ive tried everything, y wont it work?!?!?

anyone?

For the computer with the USB wireless adapter check the WEP settings. Also check the router's WEP settings too to make sure they coincide with the adapter's WEP settings...also make sure all your settings are properly configured. I don't have that much experience with wireless networking, so I can't help you too much.

Thanks