I'd rather not limit myself to having to use one type of computer just because it's not worth a virus writer's time to write a virus for it. I'd rather pay less and just not be a dumbass when it comes to avoiding viruses. Unless you're running your mac without any anti-virus, then you're not really doing anything you couldn't do on PC.
And yes, I think mac's are shitty. My roommate had one and I hated trying to do basic things on it that took me 5 seconds to do on a PC. The window thing that microsoft copied in vista is cool, but not anything major; the rest I hated the OS for.
Most of the mac's I've seen are built as a stand alone unit with everything integrated, there isn't enough space in a lot of the popular units to put a real graphics card or an extra hard drive.
PC gaming isn't dying, it's just getting more specialized. FPS, and RTS control a shitload better on PC than on consoles; and that's the majority of what is unique to the PC or at least hits the PC first. MMO's are still 99% for PC's as well, and those are far from dead. I'm sure the 100 million per month in revenue from PC games makes someone care about them.