Greetings --
You don't.
There is no way to reboot a WinXP PC into Real Mode DOS unless
you've set up a dual-boot system. The WinNT family of 32-bit
graphical operating systems, of which WinXP is the latest generation,
has never used or included MS-DOS. The closest they have is the
Command Prompt window.
WinXP, like its predecessors WinNT & Win2K, is a pure 32-bit GUI
OS, and does not include or "ride upon" any version of DOS, as did
Win3.x & Win9x/Me. WinXP does include a command-line emulator for
those times when GUI applets are unnecessary/redundant, but it cannot
be started in "DOS mode."
Simply boot from the WinXP Upgrade CD. You'll be offered the
opportunity to delete, create, and format partitions as part of the
installation process.
Bruce Chambers
--
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