Mac OS X users will probably notice that Apple does not offer an out-of-the-box method to do a clean installation of Mac OS X Lion (the latest version of their operating system) on an existing computer, given the App Store only distribution method of this upgrade. While there are various ways floating around to create bootable DVDs and USBs with the Lion installer, these methods can only be used if you have not already installed Lion, as the original App Store download is removed once Lion is installed. To alleviate this issue, Apple has released the Lion Recovery Disk Assistant utility which allows you to create a bootable external drive for the Lion installer, if your computer is already running Lion (just in case you need to do a clean installation in the future). The utility can be downloaded from support.apple.com/kb/dl1433 .