While I hate to continue what was already a ridiculous conversation, it's Friday before Christmas and a good 2/3 of my company is on holiday break. If I can't be drinking fine Belgian ale in the office, at least I can argue on the Internet.
PC's still have the vast majority of the market, therefore there is more support and selection of software.
You're still stuck in the gamer world. PCs having a big market share only matters if you're talking about an industry model based on repeated sales of new software titles. It makes no difference anywhere else, and certainly has no bearing on the merits of either platform from a technical standpoint.
Macs are limited in their hardware and you can't customize their internal components as much as you could a PC. That alone gives a huge variety of hardware configurations.
This would only be noteworthy if Mac hardware was substandard or if Macs weren't actually PCs running a different BIOS and OS. But most of what grants a huge variety of hardware configurations is the expansion bus and Macs have had PCI and firewire for years now.
It is true that you can choose from a wide variety of memory and disks and CPUs when building a PC. Consider the end result though, and think about it in terms that don't involve being able to eat at McDonalds for a week with the money you "saved" building a low end PC. Are you really gaining anything in terms of features or stability by being able to build your own PC that is unobtainable in the Mac world?
You can't build your own macs, you can build your own PC's though. As I said earlier Windows also promotes technical know-how, which is very important these days.
Windows promoting technical know-how doesn't preclude the Mac from doing the same, and you really should be careful to not confuse the hardware and software side of things.
Becoming a crackerjack PC technician doesn't elevate you to godhood, it elevates you to the level of an appliance repairman. Knowing how to build a computer is frankly not the herculean task in 2006 that it was fifteen years ago. In fact, the toughest thing about building a PC is wading through the marketing hype to figure out what the components are really capable of. Actually assembling a working machine and installing the OS after purchase only becomes mildly annoying if you're dealing with substandard hardware or drivers.
You also need to consider that a lot of the "technical know-how" one gains from years of working on PCs is very specialized and applies only to PCs themselves. Things like knowing about CAS latency, being able to troubleshoot IRQ problems (yes, it still happens), the ability to overclock that extra 20MHz out of a CPU.. none of those are useful outside of the computer world, and all of them are solved problems if you're using a Mac.
You mention Windows (the OS) promoting technical know-how but in comparison, I feel that much more can be gained in terms of useful technical knowledge from using Unix regularly.
