Hi all, Recently, my friend gave me a pendrive which consists Mac OS X Lion installer, but She forget where She downloaded this installer last time. So, how to know whether this installer is officially downloaded from Apple App Store? How about if lastly I found that this is an unofficial Lion installer, can I still use it to run and install Xcode 4.3? Can I still use Xcode to submit app if my Mac OS platform is not officially downloaded from Apple App Store? This is my first time install Mac OS X. Any comments and suggestions are welcome. Thanks a lot.