It really depends. If you still working for J2SE 1.4, you might feel that J2SE Tiger has lots of new features, which is quite different from 1.4.
Thus, in the absence of cert. books on Tiger, you might only rely on JLS, which is not that easy to pass this exam. As Kathy also mentioned before, SCJP Tiger will be much more difficult than that of SCJP 1.4.