We need to know whether it is a wireless card problem or a networking problem.
Is your card detected and the driver installed but you cannot get on the network
or is your card not detected or can't find the driver? In the latter case
network manager will show no device. In the former case there will be a wireless
device but no network. If you right click on Network Manager in the system tray
does it say Enable Wireless?

Also, from a terminal type lshw and tell us what it says under network adapter.