Hi Nils
If the Rules Roundup(RR) is the only test you've done to gauge where you are in terms of being ready for the
SCJP, I would say no. The RR is quite straight forward once you stop watching the cows and concentrate on the questions
You may want to try a few more exams to see what areas you are strong/weak in
http://www.javaranch.com/maha/_Mock_Exams/_mock_exams.html Try Marcus Greene's as well as they are more of an indicator to see what level you are at
there are loads more mocks out there these days
rgds - Jim