It's processes that are run as a Super Administrator - or processes that are system wide that need access privileges. There's more on Superuser on Wiki.
i just bought this PB from someone and under user in activitymoniter is the person name?
say under processor name is SAFARI and under user is DAVE.
how do i get my name there?
is there anything else i shoud know that is important about activity moniter?
That's the name of the account that he set up originally. Do you have the original DVDs/CDs that came with the PowerBook? If so, then you may want to wipe the drive and reload the OS from the discs. At that point you can set up your own account.
I would say for safety sake to buy a copy of Panther (10.3), Tiger (10.4) or Leopard (10.5), depending on the type of PowerBook you have, off of eBay. It will come in handy down the road.