Microsoft SMB Community Blog : What version of SQL can I use if I buy SBS 2008 Premium?:
http://blogs.msdn.com/mssmallbiz/archive/2008/10/13/8996462.aspx
Answer Yes.
Customers who received SQL Server 2005 Standard Edition with their SBS 2008 Premium can continue to use it after the shipping period ends, but they may not use both SQL Server 2005 Standard Edition and SQL Server 2008 Standard Edition for Small Business simultaneously. If they choose to continue using SQL Server 2005 after the shipping period ends, they can later choose to install SQL Server 2008 Standard Edition for Small Business instead of SQL Server 2005 Standard Edition.
Thank you Eric for the clarification!
