Running Dragon Naturally Speaking on MacBook Pro
Since you are working in a laptop environment where memory can sometimes be limited, I would highly suggest going the route of setting up Windows using Bootcamp. The setup process for this is fairly straightforward (it walks you through the whole thing). If you haven't already purchased Dragon; however, there is a Mac version available. If you are planning on running any smaller, less-RAM hogging Windows applications, there are also a number of potentially-buggy options available (such as WINE) for porting those to OS X.