How to do a clean install

So apparently Leopard can't partition my hdd because I upgraded from Tiger to Leopard... So from what other people have said, I have to do a clean install. Fine with me! The only problem is... I can't, for the life of me, figure out how to reformat the hard drive! There's no option when I put in the Leopard disk, and I can't do it from Disk Utility...

Anyone have a nice tutorial?

Let me see if I understand. So, when you boot from the disk, and open Disk Utility from the Utilities menu at the top of the screen, there's no button for Erase when you select the Macintosh HD, or is the button there, but you can't click it? You are booting from the Leopard disk before going into Disk Utility, right? (just want to clarify)

I just did exactly what you're talking about on my MBP, (tiger/leopard upgrade formatted and clean install of leopard) but it worked fine. My problem was that when I booted from the disk, it appeared the disk wanted only to run setup. I didn't realize after choosing a language that the menubar appeared at the top and I could get into Disk Utility.