As you have probably noticed, there is a lack of good GPS software for OS X.
As for running Windows software on your Mac, there are three options:
1. Boot Camp. This makes your Mac "dual boot" where when you turn it on, you choose either OS X or Windows. You do have to purchase a copy of Windows. The Boot Camp software is available from
Apple as a free 'beta' (i.e. test version,) that will expire sometime this year. The final version will be part of Leopard, which will cost money. Running Windows this way makes your Mac exactly the same as any other Windows laptop of similar specs.
2. Parallels. This is software that runs inside Mac OS X that makes pretends that it is a second computer running inside OS X. You do have to purchase a copy of Windows. This is called 'virtualization', because it creates a 'virtual machine'. This means you basically have a copy of Windows running as an OS X program. The latest versions of Parallels can run Windows in a 'window', full screen, or even showing just the windows of Windows programs mixed with your Mac programs. (They call this 'coherence', see their
website for more info.) You can download a limited-time demo of Parallels (which still needs a full copy of Windows,) and the full version is USD $80. Running Windows this way works about as well as running Windows on a half-speed computer with a really crappy video chip. (No 3D acceleration, although they claim it is coming soon.) And not all hardware works right, but most does.
3. Codeweavers Crossover Mac. This is software that, instead of pretending to be a whole computer, pretends specifically to be a copy of Windows. You do *NOT* need a copy of Windows for this, as the software pretends that it is Windows. However, since it has to pretend to be all parts of Windows, it isn't perfect. They have a specific list of Windows software that works right on it, and basically no hardware works. They do have a
demo you can download, and the full version is USD $60. (Remember, though, you do not have to purchase a copy of Windows, it's just the $60.)