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Make sure you have WPA2 security enabled. Then use a strong (non-dictionary word) passphrase consisting of random letters, numbers, and acceptable characters. Even though this has to be between 8 and 64 characters, I suggest something over 30 characters.
If this is done, you have very little to be concerned. Just keep in mind that nothing is absolutely fail-safe. All we can do is to make it extremely difficult for nosy neighbors and hackers.http://www.microsoft.com/security/online-privacy/passwords-create.aspx