I need to completely restore my iMac to how it was 2 hours ago before I erased some stuff I shouldn't have. I upgraded to Lion. I want to use Time Machine...I made a backup disc of Lion...and I have the original Snow Leopard Disc that came with it. What is the best way to restore my iMac to how it was 2 hours ago? Should I use the Lion BackUp Disc I made...or the Snow Leopard?