Compatibility of the MSDN-subscription version of Vista with the retail version?

Is there a difference between the MSDN subscription version of Vista Ultimate and the Retail version that would cause the Virtual Server2005 R2 SP1 installation to fail on a PC upgraded from Home Premium (retail version) to Ultimate (MSDN subscription version)?

I have a Vista x64 Home Premium that came loaded with software from the manufacturer that I would lose if I were to overwrite it by a new installation from my MSDN subscription version of Vista Ultimate.

If I install Vista Ultimate as a brand new installation, Virtual Server installation works fine.

But if I install Virtual Server 2005 R2 SP1 after I upgraded Vista Home Premium to Vista Ultimate, I get the following error at the last phase of the installation: “Windows Installer has stopped working” and then it sends to Microsoft the attached 3 files.

I even tried Windows Installer 4.5 but it did not work either:
http://www.microsoft.com/downloads/details.aspx?FamilyId=5A58B56F-60B6-4412-95B9-54D056D6F9F4&displaylang=en

Any idea why the upgraded version fails to install Virtual Server 2005 whereas the brand new installation of the MSDN subscription Vista Ultimate works?
 

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