Is the wireless Linksys card made from plastic or cardboard. The plastic version will have a model number on the bottom and can be made to work. The cardboard card will not function. There is sometimes a clear plastic carrying case, that also will not function. The plastic card can also be inserted in the laptop 4 different ways, 3 of which will destroy the connector.
Perhaps you've been sniffing too much ether. It takes two to tango. Your plastic or carboard Linksys card needs to talk to another device. Some clue as to the maker, model, and configuration of this other device would be useful.
Perhaps if you called Linksys, they might help you identify what equipment you're using.
Hint: If you're using WEP, use the Hex key, not the ASCII key.