Just pop in the Linux installtion disk and boot up. Depending on which distrobution of Linux you choose, you can follow the easy installtion instructions, or you may have to refer to online documentation.
Either way, installing Linux on a 2nd harddrive should be straigh-forward. Just choose which drive you want to install Linux on when it prompts you.
During installtion, you may be prompted if you want to install a bootloader, like Grub, LILO, or something else, just follow the instructions and everything should be setup. Now whenever you boot your computer, you should be prompted which OS you want to boot up.
Disregard my previous post.
Men don't use Viagra because they're impotent, but because some women are just butt-ugly.