I spoke with some SQL Server 2005 DBAs. The resolution was to grant the SQL Authentication account the "sysadmin" role (and no other) on the SQL 2005 Server.
I then relaunched the EPO 4.5 install and the software created the EPO DB and tables on the SQL 2005 Server (Server B).
You were right about having the account with sysadmin privilege for installation of ePO 4.5. However, sysadmin affectively means the account has full privileges over your entire server.
So after installation is complete, you would revoke the sysadmin role and have the account database owner rights (dbo) on the ePO database (specifically the account would need db_datareader, db_datawriter and db_ddladmin roles at the minimum). Additionally, the database user should have db_datareader and db_datawriter on the tempdb database - as ePO uses temporary tables and views.
Hope that helps
Most definitely requires SQL Server role/rights "clean-up" after installation.