OK, here's the deal, in simple terms.
When you install Windows, it will (as you know) install its bootloader over your current GRUB in the MBR.
The Windows bootloader does not know or care about Linux, so you will be unable to boot to Linux, but there will be no damage to the Linux system.
In order to gain access to both OSes, you will have to:
1) edit the GRUB menu so that it knows that Windows is now also available;
2) reinstall GRUB to the MBR so that the GRUB menu is displayed rather than the Windows one (not that Windows displays a menu if there's only one version of Windows on the box, but Windows does have a boot menu config file similar to GRUB's or LiLO's, and this file is read by the Windows bootloader).
The first RedHat CD is also a rescue disk. Once you have installed Windows, you can boot from RedHat CD1 and choose 'rescue" (sorry, don't so much know the details, as I don't use RedHat).
There should be an option to boot the installed RH system; there might even be an option to reinstall the bootloader. If so, take it, but otherwise, boot the installed RH system.
This should get you to single-user mode (console login as root).
Once there, you have two choices.
You can either try to fix both issues in one go (edit the GRUB configuration file with a console-based text editor so that it recognizes both Windows and Linux, and then reinstall GRUB);
Or you can fix the issues in order of importance (reinstall GRUB to the MBR from the console login, making Linux accessible but Windows temporarily inaccessible), and then boot into Linux and fix the GRUB configuration file from a GUI text editor.
Which option you choose depends on what you feel most comfortable with.
To reinstall GRUB to the MBR, from the console prompt type grub-install
From info grub
If you still do want to install GRUB under a UNIX-like OS (such as
GNU), invoke the program `grub-install' (*note Invoking grub-install:
as the superuser ("root").
The usage is basically very simple. You only need to specify one
argument to the program, namely, where to install the boot loader. The
argument can be either a device file (like `/dev/hda') or a partition
specified in GRUB's notation. For example, under Linux the following
will install GRUB into the MBR of the first IDE disk:
# grub-install /dev/hda
Likewise, under GNU/Hurd, this has the same effect:
# grub-install /dev/hd0
If it is the first BIOS drive, this is the same as well:
# grub-install '(hd0)'
You could also read the GRUB manual
for more complete information as to (re-)installing GRUB.
You could now mount the /boot partition (if /boot is a separate partition) and load /boot/grub/menu.lst
, whichever one RH uses) and edit the GRUB configuration file with a console based text-editor such as nano
, or vi
, if these are installed and you feel comfortable with using them.
If not, you should be able to reboot and boot into Linux from the restored GRUB menu, at which point you could mount /boot and open the configuration file in your GUI text editor of choice (as root). In either case, you'd need to edit the GRUB configuration file to include a Windows entry.
Naturally, we cannot know your particular system configuration (what drive you've installed Windows to, etc), but generally, your new entry needs to conform to the example found in HOWTO Restore GRUB
There are alternative manners of doing this, from preventing Windows from overwriting the MBR by switching drives and letting GRUB remap them so that Windows thinks that it's on the first drive when it isn't (outlined in Linux+Win9x+Grub HOWTO
), or even putting Linux on the Windows bootloader rather than reinstalling GRUB (outlined in How to Dual Boot with Linux and Windows :: arul's technical site :: arul john
But the first solution is the most common, and possibly the easiest, but that depends on your needs and experience.
Hope this helps.