well, i know right away what they are and what they stand for:
CAS tRCD tRP tRAS
Column Access Strobe - RAS to CAS Delay - RAS precharge - RAS Active to Precharge Delay
i know that you want to have low values for the first three. and i've been told that the best value for the fourth number is the first + the third + 2. So, an ideal value in your case would be 6.
now, now......what they mean exactly..... hehehe
that i haven't read about in some time.... let me find a nice page for ya.
EDIT: Here ya go.....RAM Latency Explained