OP: Insert your restore discs that came with your computer. Then open Disk Utility from the drop down menu. Then click Macintosh HD, click partition, select your current partition and click the little minus. Then click the plus and name your new partition Macintosh HD. Then make sure format is: Mac OS Extended (journaled). Click on your new partition and then click options. Make sure it is set to the GUID partition map/table. Hit apply and let it work its magic. Then install Leopard like normal. Then when setting it up after the install, connect your Time Machine drive. Then restore from that drive.