I have a 500gb HD in my current iMac. Doing selective backups with smartbackup software and my 250gb hard drive, I can basically save my Music Movies Pictures and other stuff I really want to just "copy and paste" when my mac crashes. Not a full system backup. With timemachine and Leopard on the way, am I goign to need a 500gb or bigger hard drive to get the full effect of time machine? Sounds like a stupid question, but I don't know what to expect with the voodoo magic that is Time Machine.