The easiest way to copy data would be to attach a Firewire cable from the broken Mac to a working machine. Boot the working machine as normal, and hold down the T key on the broken Mac as you turn it on. Refer to this Apple site for more info: http://support.apple.com/kb/ht1661
If the disk won't mount on a working Mac, you will need to remove the hard drive. This model is easy to take apart, especially if you are just going to scrap the machine afterwards. Once you get the hard drive out of the machine, you can attach it to any computer with a SATA enclosure via a USB connection.