Netinstall

I'm trying to create some netinstall images for a client which appeared to be done ok but when one was used and a clean install was used, apparently it installed over the top.

What is the best approach on how to wipe the drive on install? Is there a customization to use or something else when the mac is first booted from the 'N' key.

Also I'm thinking of creating some Netrestore images for the individual workstations as they each have different software installed. Is this done via the client with the Disk Utility and New Image?