In addition to the various options members have suggested for Windows platforms on Mac machines, another worth looking at is one by Sun Microsystems called "Virtual Box" at
www.virtualbox.org. It's free for starters, and works well with Windows7 downloading daily Scans (takes between 20 and 25 mins) and operating TradeMaster, etc. It runs on top of the Mac desktop and swapping from Windows to Mac programs is done simply by using the dock or just clicking on the required window if it's visible on the screen - both operating systems run simultaneously so for example, you can just swap from a GPS screen on a Windows window to an Excel window (for example) in the Mac environment. Downloading and installing run simply and a virtual hard drive is created with a suggested size of 20G (but I am only using about 10 of it currently). I transfer files to and from the Mac using the Public folder as a drop box (this requires installing something called "Guest Additions" after installing the main program).
Virtual Box saves spending $100 or more on Parallels or other similar software (not much help for those already set up but new users may wish to try it).
Paul M