If you need a partition tool, try
GNU Parted
http://www.gnu.org/software/parted/
If you plan on installing Windows on a hard drive that already has RedHat, don't forget to make a Linux Boot Disk.
You will need a Linux Boot Disk to re-install a Linux bootloader (GRUB or Lilo) back into the MBR.
Also, some Windows OSes (95, 98, ME and NT) don't like it when non-windows partitions are on the hard drive.
They will try to format them.
In this case, you have to install them first.
However, windowsXP and windows2000 play nice and leave them alone.