Lost and wondering what to do...

I'm not "new" to Macs, I've had some sort of Mac machine since the nineties, but I've only used them for e-mail and word processing.

As my forum handle proclaims, I'm a ludite of sorts and may consequently ask simplistic questions, and this may be one of them:

A friend recently upgraded to a new computer and gave me their now replaced machine. It's a MAC power PC G5 running OS X version 10.4.11. I want to keep all the software on this machine, but clear it of the previous owners passwords, login info, e-mail inbox, photos, etc.

Essentially, I want to completely replace "them" and all their data -- except the installed software -- with "me" and all of mine. Is that possible. or must I clear the entire machine and install (re-install?) software, treating it as a new out-of-the-box machine?

Once I get the answer to that question, I want to learn how to transfer all the data that's on my PowerBook G4 laptop to this Power PC machine, and maybe someone here can point me in that direction.

Thanks very much, Harry

Yes,
Whenever one gets a used Mac, I recommend doing an "Erase and Install" of the operating system. In your case, you might want to consider installing Leopard as opposed to Tiger, as it is next to the newest operating system that will run on your Mac.

Thanks for the reply. So, does performing a "Erase and Install" operation maintain the already installed software on the machine in question or does that software get erased in the process?

The software gets erased. However, one can always reinstall software. Surely, a small price to pay for a brand spanking new operating system. If you don't want to do this at the moment, you can set up another administrator account in System Preferences. Bear in mind that some applications that are already installed on this Mac may not work in the new account.

I don't think I can do that "erase and install" thing. I don't have a CD or set of disks with OSX on it. Can I make my own copy of the OS ? and then do the E & I?

"Can I make my own copy of the OS ? and then do the E & I?"
Yes, but it's not legal. Have you checked out the "administrator account" link in my previous post? That would be another option.