xiao guo, This is a great group for SCEA certification. You will find many invaluble threads here. You may also want to join scea_prep. You will find the files and links sections there useful as well (besides the 1300 odd members always ready to help). Hope this helps.
Sanjay Raghavan<br />SCJP2, SCEA-J2EE<br />Moderator - <a href="http://groups.yahoo.com/group/scea_prep" target="_blank" rel="nofollow">SCEA PREP</a><br />Co-Author - <a href="http://www.whizlabs.com/scea/scea.html" target="_blank" rel="nofollow">SCEA@Whiz</a><br /><i>Where did you sip your Java Today?</i>