and shut down the machine.
Now start it up again while holding down the OPTION key.
Keep the key down until you see icons on the screen.

There should be an icon of a hard drive and one of a DVD.

With the arrow keys, select the DVD. Allow it to boot up.

If it boots, start the install of OS X but STOP as soon as you see the Menu Bar at the top of the screen.
Find the Utilities menu item and select Disk Utility.

Get Disk Utility to check the internal hard drive.

Email the serial number, via my profile, and we'll see if it is vintage on not