Peng,
Users that have DeltaV Database accounts will be automatically brought in with a database FHX import on a new ProPlus, with associated locks and keys. However, Windows accounts, with their associated passwords, will not be brought into the system.
If the new ProPlus is a Domain controller, all you will have to do is go back into DeltaV User Manager and re-add Operating System Account with associated password.
If you're in a workgroup environment, you'll have to create the Operating System account on the ProPlus, then you can right-click and replicate this to other DeltaV nodes.
You may take another approach to the operating system accounts to save time. The DeltaV Upgrade Wizard uses a combination of the Microsoft ADDUSERS utility and a freeware COPYPWD utility by SystemTools.com to export the user accounts and passwords, and import into the new ProPlus. Be careful with attempting this approach, as you don't want to trash the newly-created DeltaV system accounts.
The utilities are located on your DeltaV disk 2 (or Disk 4 for version 8 or below), in the following folder:
\MigrationUtilities\UpgradeWizard\AccountSupport
I would also recommend using the latest version of the COPYPWD utility, available from:
http://www.systemtools.com/free.htm
Hope this helps!
Jason