Recently after 2 years of my macbook purchase, due to some of my own fault my macbook stopped starting in windows, some hardware fault got developed So, I had is repaired. Once I got it back I tried installing windows with windows 7 dvd, but unfortunately super drive on my macbook stopped reading the dvd irrespective how much times I tried, due to which I stuck in the step in which bootcamp assistant tool on mac OS requires to detect the windows 7 dvd in super drive before it can start the windows 7 setup using bootcamp.
After some useless tries, I started searching on web and I came to know about a tool with the help of which you can install windows 7 on any macbook model with USB Drive, by putting the windows 7 setup on USB drive.
Firstly before you start you will need a windows 7 setup dvd and another computer where you can read it and tools called UNetbootin or WinToFlash which lets you transfer all your windows 7 setup files on USB stick and make is bootable. Please note that for this you will need a USB drive completely empty and with at least 4gb of space size.
Once you have created USB Drive with windows 7 setup on it ready, now you will need to install mac os bootloader editor tool called EFi Boot Menu & Tool kit on your macbook under mac os. The download speed of this tool will be slow, its just 6mb of size.
This tool called rEFIt allows for boot the Macbook Air from other a USB thumb drive, which is represented by the Microsoft logo with the icon of an external hard drive at one corner as shown in the image below.
Once that’s done, Boot Camp Assistant will ask to create a new partition for Windows by shrinking the existing Mac OS’ partition. Pick the new partition’s size carefully as you can’t change it without having to reinstall Windows from the beginning. The partitioning takes a few minutes, and when it’s done, you click on "Quit and Install Later."
Now, insert the Windows 7 installation thumbdrive into the MacBook Air’s USB port and restart the machine. As soon as the computer restarts, press and hold the Option key. If you have done step B correctly, you will see a little photo of a hard drive with the letters "rEFIt" underneath; press Enter and you will be greeted with the all-new rEFIt start-up options. Here you will find the option to boot from the thumbdrive, which is represented by a Microsoft flag with a little icon of an external hard drive at its corner as shown in the image above.
Once windows 7 is installed you can remove rEFIt boot menu from mac os, and revert to the old style mac os default bootloader which lets you select mac os or windows when you boot.
In order to remove it when you are booted into Mac OS X, rename or remove the “efi” folder. For a 100% clean de-installation, also remove the folder “rEFItBlesser” inside “Library/StartupItems”. I hope this tutorial helps a lot of people out there, please let us know if you face any problems in above defined procedure.