I fist came across this in the release notes:
NEW: Support for Microsoft SQL Server 2005 (SP1 only) as a
database for VirtualCenter. See Requirements for Running VirtualCenter
with MS SQL 2005 (KB 6565318) for information on using this database with VirtualCenter.
It would be nice if they updated the other documentation to reflect this.
The question is now when will they support SQL 2005 SP2
I submitted the feature request for SQL 2005 documentation update a few weeks ago.
SP2 just came out. Might take them some time to get that tested.