I voted both, being that they both have their highs and lows.
In my honest opinion, though, it all depends on what you use it for.
For corporate tasks ( Such as spread sheets, calculating, etc ), a PC would be the way to go. Windows is also much, much better for gaming, especially since Vista released ( Though Vista is a MAJOR RAM hog. ).
For designing, video editing, digital art, and things of the like, a Mac ( While much more expensive ), is the definite way to go. It just seems to play nice with programs like Photoshop, etc.
Macs are getting better for gaming, but Windows does still have it beat.
Virus wise, Macs have PCs beat. They basically don't exist. However, the reason they don't exist, isn't a very pretty one. It's not because Macs are more secure. It's because hackers/virus coders don't care about them.
There's nothing to gain from writing a virus for a Mac, since they, for the most part, aren't used in major office corporations. If Macs were more prominent in the office world, I can assure you there'd be plenty of viruses around for them.
And I, myself, being a digital artist, wish I could get a Mac, but alas, I am stuck with my PC for now. XD.