Microsoft Windows XP Home and Professional Editions are shipped with the Microsoft Data Access Components (MDAC) 2.7 stack as part of the core operating system components. Although it is possible in Windows XP to replace the MDAC 2.7 stack with an earlier version of MDAC, doing so is strongly discouraged because it puts the computer in an unsupported configuration. Any issues that arise from doing this will not be supported by Microsoft.

Upgrading to Windows XP upgrades your MDAC stack because Windows XP ships with MDAC 2.7. In some rare cases, moving to a new MDAC version can negatively affect applications that use the MDAC components. This can be due to regression issues in the MDAC component stack. New versions of MDAC are designed to support existing functionality in client applications; however, Microsoft has the following recommendations for customers considering an upgrade to Windows XP on systems with existing applications that use MDAC components:

• Test all MDAC client applications thoroughly before deploying them in a production environment on Windows XP platforms.
• If problems are found with the components in the MDAC 2.7 stack, notify Microsoft Product Support Services. Because MDAC regression issues on Windows XP cannot safely be resolved by downgrading the MDAC components, Microsoft can assign a higher priority to these regression issues and will work to resolve these problems as quickly as possible.
  
  For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:
  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS (http://support.microsoft.com/default.aspx?scid=fh;en-us;cntactms)
  NOTE: In special cases, charges that are normally incurred for support calls may be canceled, if a Microsoft Support Professional determines that your problem is a confirmed bug or regression, or if a specific update will resolve your problem. Normal support costs will apply to additional support questions and issues that do not meet these requirements.

In any event, Microsoft strongly advises customers not to attempt to resolve any suspected regression issues by downgrading the MDAC stack on Windows XP. MDAC components released before version 2.7 have not been tested on these operating systems and downgrading these components can break other applications that were designed and tested against MDAC 2.7 or Windows XP. This could have serious negative consequences for both user applications and the operating system itself. Microsoft reserves the right to limit or refuse technical support for any issues on systems where this has been done.