we use Kerberos for better security .otherwise the default is NTLM .Not sure where the issue is .
Can you share the complete error message please ..that will be helpful .
If you get the error on the setup page , there will be a page icon .Click on that and paste the information on the notepad or direscly here ..
Awaiting your reply .
Abhay Chaudhary
Sr.DBA (MCITP/MCTS :SQL Server 2005/2008 ,OCP 9i)