Ooo, ooo.  I know an answer to one....

Andy:

Use DOS debug:

 ----------------------------------------------------------------
      Debug        Enter Debug       Comments
      Prompts      Commands
   ----------------------------------------------------------------
      -            A 100             Assemble from CS:0100.

      nnnn:0100    INT 13            Call interrupt 13.

      nnnn:0102    press the         (nnnn in the segment address).
                   ENTER key

      -            RAX               Replace AX register.

      AX 0000

      :            0301              Write on sector.

      -            RBX               Replace BX register.

      BX 0000

      :            0200              Start from ES:200.

      -            F 200 L 200 0     We want to write zeros.

      -            RCX               Replace CX register.

      CX 0000

      :            0001              Cylinder, 0, sector 1.

      -            RDX               Replace DX register.

      DX 0000

      :            0080              First physical hard disk, head
                                     0. (Substitute 0081 for this
                                     entry if you are clearing the
                                     table on the second physical
                                     hard disk, 0082 if you are
                                     clearing the third physical
                                     hard disk, and so forth).

      -            P                 Proceed (Debug will display
                                     several lines of information).

      -            Q                 Quit Debug.


Carefull, Carefull.  Use at your own risk.. This came from microsoft and
I've used it to delete non-dos partitions and DOS.

Scott