Ok so il explain my situation... At the moment i have the latest version of mac OS... on a 120gb hard drive, ive time machined my current hard drive onto a 250gb external USB hard drive... I only have the old version of mac OS on disc.. not the latest.. (leopard?) i cant remember the names... WHen i instal my new internal 320gb hard drive, can i just use disk utility from the old mac OS disc, then backup from my external? Will it then be back to the new version of mac OS? thanks.