i used to use delpart, but it has trouble with newer hard drives. these days i normally plop in freedos cd and use xfdisk, or use some linux live cd and use its dick partitioner (cant remember what its called). of course most of the time you can delete and recreate partitions with the windows installer. regardless you just want to delete the partitions, and let the installer for the os decide what do do with your drive.
also really depends who you're giving it to, if you're giving it to a computer geek i wouldn't even bother, they would probably just re-format the drive and install some linux or partition the system in a way they can use. giving it to somone who doesnt really know a whole lot and just needs a net box, a basic restore is enough. now if its a computer with one of those restore cds and not a whole lot else, and your giving it to somone who is really dumb on tech, id go into the os and idiotproof the **** out of it.