IMHO the cleanest way to have both systems independent of each other is putting LILO or GRUB at the root partition of your Linux installation (typically / ) and using a "clean"third party loader to manage both worlds.
The best boot manager I have met so far is OSL2000 ( www.osloader.com ) which puts just a few kilobytes at the HD bootsector, can boot anything from anywhere, installs and uninstalls 100% safely (preferrably from a boot diskette, although it can also be done from Windows), backs up your old MBR, and it is uncrippled shareware (no time or functional limitations, just some random naggers at startup for the unregistered version).
As for the missing GRUB, if you have not made an emergency diskette you have to boot back from RedHat CD and repair your installation. You will be prompted at the end about where to put grub/lilo.
The revolution cannot be a lever, or an essay, or tablaeu, or embroidery. It cannot proceed mellowly, piece-by-piece, gently, devoutly, simply and humbly.
Mao Zedong