How can I install Windows alongside Ubuntu?

I recently installed Ubuntu and love everything about it except for one thing: I can't use Adobe Illustrator. When I installed Ubuntu, I reformatted the hard drive. Now I want to partition the hard drive and install Windows 7 alongside Ubuntu. How can I do this?

Solution 1:

This is the official document by Ubuntu team on Dual Booting Windows 7 and Ubuntu .
You will find all the required step there .
Just install Windows before you install Ubuntu or you will end up repairing your grub
Installing an OS on external hdd will make it really slow , a better option is that you use Virtualbox for the os that you are bound to use less