If WEP is the only option available to you, then use it. As Brain_Damage is suggesting, it would be wise to upgrade your router or wireless network card to one that supports WPA or, even better, WPA2. But WEP is still better than nothing - I don't personally know anyone's kid sister who would have the first idea of how to crack WEP encryption! An amateur hacker, on the other hand, will be able to download the aforementioned tool from the Internet and decipher your WEP encryption key. But only if he's near enough that he can detect your wireless network signal, which usually means being in the house next door, or next door to that, or sitting in a car outside.