Not sure what you mean. There is no DOS in XP but there is a DOS emulator (Command Prompt) which has all the same characteristics. There have been a few changes to commands since W98 if you Google around but most of the old ones are still there.
If you can't find it in the Start Menu then just type this in the Run box:
cmd.exe
Windows XP has no DOS so you can't put it into DOS Mode. You can use Command Prompt (cmd.exe) for Commands and Batch files only.
when u start your computer press f8 on bootup it will show you some option chose command prompt frm tht ok . . . . enjoy your DOS
Regards above: http://support.microsoft.com/kb/315222 Command Prompt is CMD.EXE
NTVDM is COMMAND.COM
http://en.wikipedia.org/wiki/Virtua...
Neither are MS-DOS, that O/S died with Millenium Edition...