There are a lot of comments here both for and against the use of Macs and PC's.....
I have been a long time user of both Windows, Mac and Linux (and still am!).... all have their pros and cons.... i guess there are three things that it boils down to:
1). REQUIREMENTS -
what is the system for; how much perfomance is required...
2). BUDGET -
£40k Mac Pro video editing system; £600 laptop for portability and terminal services...
3). LONGEVITY -
notebooks and laptops have a short lifespan when compared to a desktop system...
I've used a substantial variety of systems in my time; but i couldn't pick one system that does it all...
If you're planning on purchasing a new system, assess the three criteria above, read up on both features and flaws of prospective machines (if i knew my MacBook Pro would get hot enough to cook eggs, i might have thought twice!!) demo the systems if you can, ... and above all enjoy your new tool!!!