***Ooops! Title should say 10.5.6 installer**** Hi Trying to recycle my wife's old (but still perfectly servicable) 2008 20" iMac to a new home. However, the 10.5.2 discs it came with are long gone. I tried using the 10.5.6 installer discs that came with my 2009 24" iMac but just get a "OS X cannot be installed on this computer" message. I understand why it wouldn't work the other way round, but why can't I put 10.5.6 on an iMac that would have only been 1 year old when it came out? Is there anyway I can do it? Cheers anyone.