Mac vs PC... the answer is simple:
The more you use something, the better quality it should be. Therefore you should get the best quality you can afford, otherwise operating and maintenance costs (including time spent dealing with those) make the initially cheaper product more expensive in the long run.
Therefore if you don't use your computer much, get a cheaper Windows PC or even a net-book. If your life depends on your computer, get a Mac, even if only a refurbished one because durability, design, stability, and resale value make it better in the long run.
If you can't afford a Mac and must settle for a Windows PC, then you'll still pay in the long run with additional time spent keeping Windows running - defragging, startup, shutdown, running spyware scanners, fixing the registry, troubleshooting hardware and software installs, etc...
For example, in 4 years I never had to reinstall OS X, and yet my PowerBook runs as fast as it always has. Never had to run a virus scan. Never had to defrag. With Windows PCs you do the wake/sleep thing for four days in a row and the system slows down considerably due to memory leaks. I can go months without restarting the computer, just open the lid to wake, close it to sleep, and it always works. See, timesavers, energy savers, convenience, stability.
You make a compelling argument but I'd like to challenge it on a couple of points.
If your life
really depends on your computer and you need it running 24/7 or you're screwed, you have to consider the possibility of a hardware failure and the impact thereof. In those cases it's a lifesaver to have NBD on-site support because then you can just call a number and some bloke will stop by and fix your machine the next day. Some PC brands offer that service, others don't (Dell will do it, and probably HP, but not Sony, ASUS, Acer etc). Apple won't do it though, so you could be without your machine for X or XX number of days depending on where you live. If you're five days from a deadline, do you want your computer back online tomorrow, or in six days?
Also, I think you're exaggerating the 'chore' of owning a PC. Defrag and spyware scanning is automatic, scheduled and built into Windows; cleaning the registry takes about a minute with CCleaner (freeware) which puts it at a total of about 4 minutes per year. I don't know what you mean by startup and shutdown, Windows Update doesn't require more reboots than Apple's Software Update does and the rest of the time you can just put the machine on standby/sleep/hibernation. That's what I do and I'm not noticing any degraded performance or memory leaks (the last reboot was 9 days ago, the last one before that was sometime in February).
I think the main reasons to go with a Mac are...
- if the OS X desktop paradigm is more in tune with your thinking and your workflow than the Windows one is
- if you're a sucker for stellar industrial design
- if you're a musician who needs low-latency audio without a lot of tweaking to get it right
- if you'll be working in an environment where Mac dominates and you don't want to be "that PC guy" (you can probably handle the friendly banter, but more importantly there can be minor cross-platform incompatibility issues with fonts, some file types etc that can cause some unwanted friction)
- if you need software that doesn't exist for Windows (Logic, Final Cut etc)
- if you are an absolute computer beginner (not saying Mac is for n00bs but there's less chance of screwing up the system, and the learning curve may be somewhat in Mac's favor)
As for this whole virus/stability/maintenance argument... that's a little anachronistic and I don't buy it, sorry. Macs need some maintenance too (Onyx, Disk Utility), they do crash sometimes, and viruses on modern Windows PCs are something you have to actively force onto the system, they don't drive in through open doors anymore.