How to make 2nd hard drive a bootable drive

Hello,

I have two SATA hard drives installed in my Dell 8400 desktop computer. Both drives have Windows XP installed as the operating system. When I go to 'My computer' I see both drives and can transfer files back and forth between the two hard drives. However when I do an f12 command during startup the 2nd drive does not show up as an available boot drive. Similarly when I go into system set-up with the f2 command the 2nd drive does not show up as an available boot drive (it does show up under "Drives" as an installed and activated drive.

How can I get the 2nd drive set-up as an available and alternate boot drive?