I have two different sets of back up discs that came with both my imac and macbook... a buddy is selling me his old emac - he has already wiped out the hard drive leaving me with no OS. Can I use the back up discs that came with my newer computers to install an OS on the emac or will i need to purchase a new OS version? (I know that the emac will support the OS - but will the discs allow me to install or is it a liscence issue?...) Thanks in advance for your wisdom.