I recently reinstalled windows XP and decided to dual boot it with Fedora Core 3. I have XP installed on an 80 gigabyte master hard drive and I installed Fedora Core 3 on a 40 gigabyte slave. The installation went fine but when I rebooted the machine after the installation the bootloader does not show up and Windows XP boots up. I tried installing again and the same thing happens but this time during the installation it told me that it noticed another linux installtion on the 40 gig drive. Any advice with how to get them to dual boot?

Put in the FC3 rescue disc and follow the instructions on screen. Once inside, run the command /sbin/grub-install /dev/hda

This should install the boot loader to your MBR and let you choose between OS's when you boot.

most likely you either:
(1) didn't install a bootloader; or
(2) installed it in the wrong place <-- most likely.
Try booting from the linux disk (fx. by making it master).