I've been similarly frustrated - apparently strong connection but no connectivity, caused by using the wrong key. "Admin" sounds rather like what would be used for the router itself as opposed to the wireless connection.
Can you access the router from another connection? Open a browser & type in the IP address for the router (Google the router model for the default if your friend doesn't know) - you'll then be prompted for a username & password, again Google the defaults if it's not known).
Click on "Wireless Settings" & you'll get a page that should show the WPA key, if that's what is being used.
You could also get Windows to reveal the key on a known good laptop:
WirelessKeyView: Recover lost WEP/WPA key/password stored by Wireless Zero Configuration service