Exactly, Google "Cracking WEP." All the information is there for anyone to use. Hell, even Tom's Networking, a sister site of Tom's Hardware, has an article on cracking WEP.
If I remember correctly, WEP uses the same security code each time information is exchanged, so for the most part, all someone needs to do is collect a packet sent by the router to get the code and crack it. WPA changes the security code each time, therefore, its near impossible to crack, as the person would need the main security code, which is the one you sent.