Thank you for your time. As we discussed, here is a summary of the issue:
Detailed Issue Definition
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You have a customer who is planning to install Small Business Server (SBS) 2003 Premium Edition but instead of using the SQL Server 2005 workgroup edition they want to install SQL Server 2005 Standard or Enterprise Edition as their LOB application will not work with SQL Server 2005 Workgroup Edition.
You wanted to know if this is a supported solution or not.
Agreed Resolution
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We discussed the solution and agreed that I will be sending you an email and then close the case.
Current Status
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As discussed, it is possible to install those products (SQL Server 2005 Standard or Enterprise Edition), but this configuration is NOT SUPPORTED by Microsoft. A better configuration would be to add another member server running Windows Server 2003 Standard Edition and then install the version of SQL Server on the member server.
Also, If you have licensed a copy of SBS 2003 R2 Premium Edition but your vendor has not certified a line-of-business application for use with Microsoft SQL Server 2005 Workgroup Edition (the version of Microsoft SQL Server that ships with SBS 2003 R2 Premium Edition), you may be entitled to exercise an “one-time” downgrade of your SBS 2003 R2 Premium Technologies CD to SBS 2003 SP1 Premium Technologies CD, which includes Microsoft SQL Server 2000 Standard Edition. After exercising this Premium technologies downgrade right, you may run the version of your line-of-business application which is compatible with SQL Server 2000 Standard Edition.