The Fdisk command allows you to modify...(create, delete, view) seperate partitions on a hard drive. While the Format command simply formats the hard drive (or partition).
If you want the C drive to be your primary drive to install Windows then the command is:
you can also add the following sytax to the end of the format command (however this is not necessary):
/Q Performs a quick format.
/B Allocates space on the formatted disk for system files.
/S Copies system files to the formatted disk.
/1 Formats a single side of a floppy disk.
/4 Formats a 5.25-inch 360K floppy disk in a high-density drive.
/8 Formats eight sectors per track.
/C Tests clusters that are currently marked "bad."
/U Completely erases all data on the target disk making it impossible to perform an UNFORMAT later.
/V Displays a prompt so that a volume label can be entered.
There are more, just do a Google search for "format command" or "MS-DOS format syntax"
If you have any more questions just let us know.