Whether you've got a MacBook Air/Mini (2011) or any other Mac with an optical drive, installing Windows from a USB drive is just the more comfortable option: first, the setup is done in half the time, second, this thumb drive is also a more portable Windows Recovery Environment. It doesn't scratch and fits easily into your travel bag -- if your system gets messed up, plug it in and run the repair options. Here are a couple of ways to create a bootable key (remember, you're going to need at least a 4GB stick):

: Launch the Boot Camp Assistant, check "Create a Windows 7 install disk" and hit "Continue".

Make sure that the proper USB drive is selected and hit "Continue". Et Voilà! The ISO gets "burned" to a bootable Flash drive. Now, read the rest of the instructions given in Step 1 above ("Setting up your Boot Camp partition").

: The easiest way to create a bootable Windows 7/8 Setup USB Drive is with Microsoft's own "". Download it, select an ISO and the target USB drive -- and you're done!

(Hint: If the USB thumb drive isn't recognized by your Mac bootloader or rEFIT, try creating the installer using -- and if all fails, the manual route should ).