I found an interesting article from Warren in the VMware community about the limitations of using SQL Express as the VirtualCenter database server. Beware of SQL Express & undocumented loss of some important features in VirtualCenter, confirmed by VMware. Just a quick note to warn people away from "upgrading" to SQL Express with VirtualCenter 2.5. If you do, you will probably be sorry. Due to Microsoft removing the SQLAgent in this "lite" version, there is no automation. This means that there is no way for VirtualCenter to do things like roll up the daily data into weekly and monthly views, or perform scheduled truncations, cleanup or backups. They will be noting (some of) this in some future release of the documentation, but it's not in there today. Please see http://communities.vmware.com/message/832082 for details on my problems with missing performance data. In that thread you will find reference to a couple service tickets that you can reference in your communications with them, if you bump into this or related issues.