|Can you cut your legs off while running a race?|
The same is true in trying to format the drive when in windows. You could not do the same thing in Win98 either.
There is no good reason to want to format via dos when you can use the xp install disk to do the same or any number of other programs.
Just remember that you have to boot up on floppy or cd to format the disk.
BTW the command is format c: /s otherwise you don't make the drive bootable via dos.