To make a long story short, I have WinXP and Red Hat 9.0 installed on the same hard drive in my laptop. Previously I had been using the GRUB bootloader to choose my OS, but I had to re-install Windows ...

I assume the 120GB drive is the primary slave. In that case, your problem isn't with grub, but rather with the windows bootloader, whichc doesn;t like the drive order being changed on it. You need to ...