if you chose the NTFS option when you installed Windows,or when you formatted from the CD, or your computer was supplied with NTFS as default, you won't be able to format the hard drive from DOS.
When you boot form the floppy drive you'll see this:
If you type c:
You should see this:
If you don't, then your hard disk is probably NTFS, and you can't format it from DOS.
You can use FDISK to partition it, but you can't format it from DOS.