I just got a brand new internal 2.5" internal hard drive for my MacBook Pro. I have OS X Lion on my current internal hard drive. When I go to the App Store to try to redownload the installer .app it doesn't let me. I also could use an external hard drive, as I have one. So that leads me to my questions. Is there a way I can redownload Lion from the App Store so I can install the OS to my new HDD after install or Should I use Time Machine to back up my current hard drive, install the new HDD then install the Time Machine back up onto it?