Looks like a G4 but hard to tell from you pic, like someone already said google the serial number as powering up and looking @ about this mac will only tell you the processor and memory
That's definately a MacBook pro as it has a camera.
G4 is a mac pro, as for setting to back to factory default http://hivelogic.com/articles/how-to-prepare-a-mac-for-sale/
thanks for your help
Cheeky b*****d.