This Article about instructions on installing Windows on a Macintosh computer using Virtual Box.
Step 1: Downloading Virtual Box
How to find the version of OS X that you have: http://www.apple.com/support/ If you are running OS X Mountain Lion or OS X Lion
Go to https://www.virtualbox.org/wiki/Downloads Choose VirtualBox 4.2.16 for OS X hosts
Install VirtualBox
If you are running OS X Snow Leopard, OS X Leopard, or earlier
Go to https://www.virtualbox.org/wiki/Download_Old_Builds Click on VirtualBox 3.1
Choose VirtualBox 3.1.8 for OS X hosts
Install VirtualBox
Step 2: Downloading Windows 7 image and obtaining license from Dreamspark
Go to http://software.yale.edu/Library/Windows and log in with your netID and password
Find the Dreamspark link and click on it.
Choose Download Now
Search for 'Microsoft Windows 7 Professional'
Under 'Download', choose 'Microsoft Windows 7 Professional 32-bit (English)"
Choose the one that is "Available to: Students/Faculty/Staff"
Click 'Add to Cart' and proceed with the checkout
NOTE: you need to save the serial number, as you will need it later
Click 'Download Now' and follow the instructions to download the Windows image (.iso)
Step 3: Installing and licensing Windows on Virtual Box
Copy the Windows 7 .iso file to your Desktop or another memorable location.
Open Virtual Box.
Click 'New'.
Put 'Windows 7' in the name field and change the Operation System Version to 'Windows 7' (NOT 'Windows 7 64-bit). Click Continue
Set the RAM to anywhere between 1024MB and 4096MB, up to about 1/2 of the available max. If you're not sure, 1.5 GB may be a good choice. Click Continue
Select 'Create a virtual hard drive now'. Click Continue
Select VDI (VirtualBox Disk Image). Click Continue
Select 'Dynamically Allocated'. Click Continue
The name can be left the same. 15 GB may be enough for use of one program and some files, but this choice is up to you.
Click 'Create'
Click on 'Settings' and select the 'Storage' tab.
Under 'IDE Controller', click on Empty. Then on the right-side column, click on the CD icon to the right of 'CD/DVD Drive' and select 'Choose a Virtual CD/DVD File'.
In the Popup WIndow, find the Windows 7 .iso file you saved earlier and double-click it.
Click OK to close the Settings Window.
Click 'Start' and a black box will pop up. Follow its instructions to install Windows 7.
Choose "Custom (Advanced)" Installation
Choose the only disk available, and continue.
Enter a username when prompted, and set a password.
Enter the serial number when prompted.
"Use recommended settings" for security settings
Set time zone appropriately (New Haven is -5:00).
Select "Public Network".
When prompted for a serial number, put in the key that you got from Dreamspark earlier.
Step 4: Enabling Campus Printing (optional)
These steps won't work on all computers because VirtualBox's "Bridged Adapter" setting doesn't always work. If not, you can print to pdf and email them to yourself.
While the VM is running choose "Devices -> Network Adapters..." in the top bar of VirtualBox (not in Windows).
Set "Attached to:" to "Bridged Adapter" and save.
Verify internet works (via an internet browser).
Test print from any application. It may take up to 15 seconds for the NetID popup to appear.