vCenter Single Sign On DB options

Hi there

I want to migrate vSphere 4.1 U1 to vSphere 5.1, before going forward with the in place upgrade, we trying to recreate the scenario, so I've created a whole vSphere ambient with 3 host and vCenter, everything is just fine until here.

I'm following this guide hxxp://deinfotech.blogspot.com/2012/10/upgrade-vsphere-41-to-51host-agent-check.html

Our configuration is as follows:

vCenter on a virtual Machine

vCenter is an remote Oracle DB (10G R2)

vCenter update manager is an SQL express locally instaled DB.

So I wonder which are my DB options, i.e.

Can I just install the Single Sign on DB alongside the existing sql express 2005 vCenter update manager DB?

Can I create another DB instance for Single Sign on in the SQL express 2005 existing installation?

I supposed that I can migrate the SQL express 2005 update manager DB to a full SQL server 2008 R2 and then create the DB for SSO.

Thank you