VM Fusion

You can download an ISO of the Windows 7 install and mount it using VM Ware fusion to initialize the install.

Not sure if you've purchase VM Ware fusion yet, but a free alternative that works well is: https://www.virtualbox.org/

 

I second the use of virtual box. It's a great bit of free software and I've got it working perfectly on a 2011 MBA.

 

Havent used VBox on my MBA just yet.

But i do second it's use if you can. We at work have completely moved away from using VMWare towards VBox. not only is it free, but there are a lot of very good options with few limitations.

And free

 

I use vmware fusion for headless development VM's on late 2010 model (most of them are ubuntu) have not had problems at all, not even when running several at once.