Format confused wont run in DOS

[needhelp]

I have been helping a friend format his hard drive and reinstalling XP.
He had NTFS partitions on his hard drive. so I ran Delpart and deleted the partitions. so far, so good. I then ran fidsk and created primary, extended and logical drives as usual with the primary DOS partition set to active. no problems. But the next step has me confused.

The next stage was to format the partitions so I typed format C: at the A: prompt as I always use to do and I get the message "format cannot be run from DOS" (words to that effect)
Now, why is that, I always thought the format command was a DOS based thing and it always did the job in the past when I did it this way.
I got to the DOS prompt via a ME floppy boot up disk.which has has the format command on it.
I got around this by changing the boot up sequence to CD first choice and formated the C: drive during the XP set up procedure and formated the other partitions from XP Disk management once XP was installed. But why cant I do it the old way. I always formated the hard drive from the A: prompt by typing format C:
I have been on several sites on formating hard drives and this method is still detailed in some of the sites I have been to.
I am confused and wonder if someone could put me straight on this matter. I know someone will.

[Cricket]

WinXP does not use DOS at all and you don't prep the hard drive the way you would for Win9x/ME. For future reference you can use the installation instructions found here.

Cricket

[glc]

Fdisk can't make NTFS partitions anyway. Do not use a bootdisk when you are working with Win2K or XP, it's all done with the installation CD.

[needhelp]

Thanks guys, much appreciated.