Grub, the bootloader, needs to be installed on the mbr of the first hard drive and be setup to boot windows too.

I'm not familiar with the redhat setup, only SUSE.

It should give you options as to where it installs grub and what other partitions it can boot.

It should see windows and have that option.

However if it is not placed on the first disk mbr it wont be found as this is where the system is booted from.

Unless you want to turn discs on and off in the bios, might be able to do that depending on your model.