Wiping a mac hard drive?

Hi

I recently made the stupid mistake of trusting a friend thinking he knew what he was talking about when he used a third party partitioning program on my computer. Problem is I can't remove the partition now and boot camp won't work with it on the hard drive. I've tried wiping it by reinstalling OS-X and having everything get erased in the possess but the partition didn't go anywhere. Also the disk utility can't really do anything to the partition. Outside of that I don't have much of an idea what to do. Can anyone help me? I don't mind wiping my hard drive again but I want to loose this partition.

Thanks

Did you boot the machine with your Leopard DVD disk one and run the Disk Utility direct from there? You can not use Disk Utility to erase or otherwise remove all partitions when the machine is booted from the internal hard drive.

Regards.

No I didn't try that. I'm guessing there is a key I have to press during startup?

With the disk in the slot, on startup press and hold the C key til the menu pops up.

thanks