Using Linux, with ndiswrapper for the wireless card, and using the command line to connect, I was having trouble connecting to a wireless access point with a WEP key until I put the keyword “open” in front of the string. If you’re pretty sure you’re entering the correct key and ESSID for a WEP encrypted access point, but still having trouble connecting, look at the man pages for iwconfig and see the examples under the section labeled “key/enc”. You’ll see the keyword “open” in one example and the keyword “restricted” in another. You might have to try each of these if you don’t know which to use. Although in the man pages, the “open” example doesn’t have a key, you can add the key just like in the “restricted” example.
iwconfig eth1 essid MyAccessPoint key open c2fccef3d1