Q253626 may have been retired. Here is what it used to say:

The information in this article applies to:
- Microsoft Windows 2000 Professional
When you upgrade from Microsoft Windows 95, Microsoft Windows 98, or Microsoft Windows NT to Windows 2000, the Setup wizard displays a warning message informing you that your current operating system will be replaced if you continue. Windows 2000 does not contain an uninstall feature to let you return to your previous Windows operating system.
You should make a complete system backup before you upgrade to Windows 2000. Restoring this backup is the only way to return to your previous operating system as it was before you performed the upgrade.
For additional information about related topics, click the article number below to view the article in the Microsoft Knowledge Base:
Q250456 How to Manually Remove Windows 2000 and Restore Windows 95/98
Additional query words:
Keywords : kbenv kbsetup
Technology : kbwin2kProSearch kbwin2kPro
Version : WINDOWS:2000
Issue type : kbinfo