Hello,
You can perform an upgrade to the 11d QuickStart Edition from 10d QuickStart Edition .
Backup exec 11d now uses SQL 2005 Express database and 10d uses Msde as a backup exec instance.
Hence durning the upgrade from 10d to 11d by default backup exec will be installed on the SQL 2005 Express database from Msde.
Hence we would request to start a fresh installation to 11d instead of upgrading to 11d.
Thank You,
Shweta