Ipconfig...media disconnected

Hello need some help. Working on a wireless network with a linksys G wireless router and 2 computers connected by wireless cards. Both computers have the same card, updates, and software installed and one works fine. The other I have been unable to get to connect. The wireless card shows up, as well as the wireless connection. Sometimes the actual network shows up but I am unable to connect. When I do an IPconfig it comes up as media disconnected and I have no idea how to change this and think it could be what my problem is. Any help appreciated.

thanks
michael

What are the wireless router settings for
WEP
WPA
Mac filtering
Channel

What windows is on the one that does not connect?
Do you have a firewall (xp has its own - is it on?)