>I'm putting together some table to manage users, roles, and rights.
>
>Anyone see any problems with encrypting all the data in all three tables?

I'm working on a similar thing at the moment. Your needs are probably different but I decided:
(a) To handle the encryption in a tier that will make it back-end agnostic.
(b) To only secure the password - and then by hash value rather than encryption.

FWIW, here's the class I use for hashing/comparing.

    static public class HashFunctions
    {
        public static Byte[] GetHashValue(string s)
        {
            byte[] source = ASCIIEncoding.ASCII.GetBytes(s);
            return  new MD5CryptoServiceProvider().ComputeHash(source);
        }

        public static bool CompareHash(byte[] first, byte[] second)
        {
            bool equal = false;
            if (first.Length == second.Length)
            {
                int i=0;
                while (i < first.Length && (first[i] == second[i]))
                    i++;
                equal = i == first.Length;
            }
            return equal;
        }

        public static bool CompareHash(byte[] b,string s)
        {
            return CompareHash(b, GetHashValue(s));
        }
    }

The password is stored as a byte array (varbinary() in MSSQL)