Hi everyone. Hope you can help me.

Since I am new to the Mac and used to Windows, I'm having lots of trouble with it and I am in need of your help.

First of all, we didn't bought the computer, a friend give it to us. The computer was a office computer (I mean, used for work), so everything is messed up because it was suppose to have 1 central Hard Drive in the office for all computers, so nothing works here.

Anyways, I need to "format" my computer so I can have full use of it and free my Hard Drive. But we do not want to format it completely (taking out the Mac OS X 10.1.5), just to put it back to how it comes when you buy it (no programs intalled).

So if you guys can post here a guide or a link to a guide, it would really help me solve this.

Computer Information:
- Computer: Power Mac G4
- Operation System: Mac OS X 10.1.5
- Ram Memory: 1.25Mbs
- Processor: 2 x 450(or 400)Ghz