There's gotta be a dusty old DOS shareware utility to be able to cause
a CTRL-ALT-DEL from a BAT file. This assumes you find one. Look in
the old simtel archives;
http://www.eunet.bg/simtel.net/msdos.html
Install DOS and XP so that boot.ini has two entries; one to boot to
DOS as a default and have XP as a second choice.
Make two copies of this file; call them bootDOS.ini and bootXP.ini
Edit each of them with a text editor so that bootDOS.ini has DOS as
the default OS and bootXP.ini has XP as the default OS. The format is
obvious.
Boot into dos and write an autoexec.bat script that copies boot.XP
to boot.ini and reboots.
Boot into XP and write a startup script that copies bootDOS.ini to
boot.ini and reboots.
This G*g awfull mess will flipflop between DOS and XP.
OR
You could join the 21st century and buy a copy of VMware or Microsoft
Virtual Machine and run DOS as a virtual machine under XP.
What are you trying to do in DOS ?