Best way to format a Mac drive?

I have a laptop hard drive that needs formatting - the laptop is dead but I have taken it out and can view it on my imac as an external drive (thank you Data Boy!)
which would be the best way to format it completely? restart and re-install with Leopard install discs? or use disk utility thru my imac?

any suggestions are appreciated!

Yeah, just boot with the disk and do it that way.