i don't have any guides handy, just Google WiFi hacking. i doubt WEP's in use anymore outside of those who adopted WiFi and security pretty early and still have 802.11b routers. Everything now should be WPA and WPA2, which is kind of a pain to crack. Whereas WEP can take minutes, WPA and it's successor can take hours. And while you can do it under Windows, it really helps to have Linux since the tools are better. i've got Linux on an old laptop that i can leave running all night if need be.