Why won't my replaced hard drive mount?

I sent my iBook to a repair shop for motherboard repair, and they told me it also needed a new built-in airport card and new hard drive. I got both parts, used your guides to replace them. The machine will boot up using my Leopard DVD, but it won't recognize a location to install the new OS. Disc Utility won't see anything either, and System Profiler says there are no ATA drives present. I checked the hard drive (a new Hitachi 120 Gb drive) and everything looks OK. I(s there something I need to do in order to format the drive, or does this sound like a connections problem? Thanks, Jim.