First, I have a 2 GHz Intel Core Duo with 2 GB ram and 80 GB hard drive. I want to replace the current hard drive with a Hitachi Travelstar 200 GB HDD, 7200 rpm etc. I'm also planning to upgrade to Leopard. What's the best way to do this? Can I just take out old drive, put in new one. Boot from old one (now being used as external) and copy old to new and then upgrade to Leopard? OR is it better to load Leopard on blank new drive and move items from old using Target disk mode? That way if I don't like leopard I can always go back to the old OS until the kinks are worked out. I've never upgraded any hardware before, nor have I ever upgraded an OS, so I'm a little apprehensive about the whole thing. I've seen other posts about this, but not about doing it the way I'm suggesting, so I'm just looking for any advice on what's the best way.