If you are dual booting W9x with Windows NT or Windows 2000, you will receive:

       	Windows 2000 Setup does not support upgrading from Windows if you have multiple operating systems                                      installed. Setup will now exit.
         Other Operating Systems Found                                      You cannot upgrade this Windows installation to Windows 2000, because you have more than one operating                                      system installed on your computer. Upgrading one operating system can cause problems with files shared by                                      the other operating system, and is therefore not permitted.
when you try to upgrade.

Microsoft does not support upgrading W9x when Windows NT and/or Windows 2000 is detected, as the upgrade is likely to overwrite common files.

To upgrade W9x, you must:

1. Remove the Windows NT and/or Windows 2000 folder.

2. Delete c:\ntdlr, c:\Ntdetect.com, and c:\boot.ini.

3. If you were dual booting with Windows 2000, delete the C:\Program Files\Uninstall folder.