Hi Billy,
You'll need to first make a change in your system BIOS so your computer
tries booting from your CD before booting from your hard drive. You can
usually access your BIOS settings by hitting your delete key when your
computer is first starting, you know, when the screen is black and the
text is white.
After you've made that change in to BIOS you should be able to boot from
a windows install CD, like 2000 Pro, and it'll allow you to format your
new drive as well as run through a setup program that will install your
operating system. Maybe a XP CD does the ssame thing, I haven't played
with one of them before.