which software to run windows on mac

I've 2010 27" iMac with latest MAX OS.X and I need to install one application that runs only on Windows XP and higher. Which software you would recommend to run Windows 7 Ultimate on Snow Leopard. I will use Windows only for one application, nothing more. It has to be easy to install and possibly free to download.Thanks

Maybe start with the sticky at the top of this forum.

http://www.mac-forums.com/forums/wi...4239-running-windows-mac-switchers-guide.html