Microsoft SQL Server 2005 Express installation fails when updating MSXML6, what can I do to fix this?

Note:  This information only applies to Windows XP with Service Pack 3 installed.  It does not apply to earlier service packs or other operating system versions.

In cases where MSXML 6 was installed prior to Windows XP Service Pack 3, Microsoft SQL Server 2005 Express (a prerequisite for ProMax) can fail to install. During the installation, the SQL Express installer attempts to check the configuration of the MSXML 6 files and fails. This failure is caused by Service Pack 3 moving the files into the Windows Protected Files under control of the operating system, but not removing the previous versions of MSXML 6 – making it an orphaned program on the system that cannot be removed using standard procedures. The failure reported by the MSXML 6 installed of ProMax will then abort the installation or other products included in SQL Express Setup that rely on XML even though MSXML 6 is loaded on the system. If you are experiencing this issue, and see the following issue during installation, please contact our Support team for a resolution.

Screen shot of Microsoft SQL 2005 Express setup dialog showing failure to install/update MSXML 6 and dependent products.