Install the drive. Insert System Disc 1 (or your retail OS X disc), turn the machine back off and back on again. Press and hold the 'C' key until the Apple logo appears. Once it boots to the Installer screen, open Disk Utility from the Tools menu, select the hard drive in the left window pane, click the Partition tab and Choose '1 partition'. This should format and prep the drive. Make sure you name it Macintosh HD. When finished, quit Disk Utility and proceed through the installation process. The rest is self-explanatory.