On the Mac side of things you have all the daily necessities available in what is generally considered a rock solid, user friendly, industrial strength operating system.
On the Windows side you have the same features (email, IM, browsing, Word) in a different package.
For daily use it's really a matter of personal preference. When you start specializing you run into a different scenario and you will also find your requirements changing as the level of technology at your educational institution evolves.
On the Windows side you will find the advantage in the area of compatibility. Most digital versions of required publications will be available on windows and quite a few will be available on the Mac (buy the hardcopy and get the digital as an afterthought). A plethora of study tools and diagnostic applications will also be 'windows only', this alone does not justify the purchase of a dedicated windows machine.
Some University attached research laboratories utilizes Macs exclusively. This doesn't mean that Windows machines are unwelcome, it just means that you will often find people's data sets in Mac native application formats. On the higher end you will find a Mac advantage when it comes to running some industrial strength software (easy unix ports), and major ease of use when it comes to viewing certain medical images.
Let's take the example of a digital medical review. In this case you wouldn't be legally networked into the patient records at the hospital so you receive your daily dose of fedex, dhl, etc. You probably won't get x-rays anymore as most institutions use Stentor/PACS/ ("Philips iSite PACS" even) in general radiology. This means you get some optical media with a bunch of digital images DICOM. I have seen the standard viewer deployed on the PC side w/ some MRI series and it's terrible. On the Mac side you get something like Osirix ( http://homepage.mac.com/rossetantoine/osirix/Index2.html ) and use QuickTime for viewing anything in an extremely usable interface.
So..let's review: D
Daily life - either platform
Restricted Database Connections - Windows
Selection of Documentation and Software - Windows
Quality of Software - Mac
Integration into existing environments - Mac.
I did oversimplify a bit of it and generalize some, but you get the idea. I think you might want to consider doing your work on a Mac and firing up Parallels for anything that is a Windows only asset. I'm sure you'll find this is a great way to work.
In my opinion having access to either platform is a necessity to your success in medical school. Let's summarize that:
PC - only runs Windows
Mac - runs Windows or Mac OS X
Kinda a no brainer like my last CT 😉
If you can get a bigger machine you might want to move all the way up to the 17" MacBook Pro, otherwise pick your Mac the same way you would pick the size of your PC.
Good Luck in Med School,
-j
Various Macs