WinOnX is a great application that allows run Windows applications on Mac OS X ,Without needing a copy of Windows. That is, it is not a traditional virtual machine, where you have to install Windows to run it on Mac, but a program that runs on Mac OS X, but being able to run Windows applications.
WinOnX is based on open source project called Wine. It is a layer that redirects the communication between an application and operating system Windows to OS X. As a result, not all applications are fully supported. Most applications run perfectly well. Some even run faster, but others run slower or even stop.
Best of all is that WinOnX only costs $4.99, an amount far fetched at all given its functionality.