You really are comparing apples and oranges. For the record Windows OS's are much more forgiving with hardware than OSX, ask the people that have tried building a hackintosh. Apple's hardware is well high quality and you pay a pretty penny for it (you could easily do the same with a PC). The few setbacks in a mac is really the compatibility with hardware as Apple doesn't ensure compatibility with certain products they feel their users won't need, including after market video cards etc.
I also didn't mean that Windows systems are picky about hardware, they really aren't. I meant down to the fundamental level of electronics. If a circuit was built cheaply, its not going to perform very well. When we start talking about transistors, memory and microprocessors for example...in transistors, if you want one that can react quicker to input signals then you pay more for a higher precision made transistor. Transistors make up memory, CPU's anything that processes data. When you pay more for high quality device, the components react much quicker, run with lower voltages, do not get as hot and are more stable at higher frequencies. When any computer crashes being a PC or Mac, its because the temperatures got too hot, and the system was running too fast which caused a hiccup in the system, errors where received and the information was not executable, resulting in that program or in some cases the whole system crashes. You could have a flawless OS and it would still have crashing programs and other system crashes because no piece of hardware will ever be perfect and hardware will still have its moments where it has errors. The only way to prevent that from happening more often is to pay more for better hardware, hardware that can run faster and cooler. That is why you pay a pretty penny for a Mac, they make a proprietary system where the hardware is based around the OS, and because of that they don't cut corners on the manufacture of the hardware. Again you could easily buy equivalent quality components for a PC build and guess what, that PC would actually cost the same as its equivalent Mac.
That's why the Mac vs PC debate is so god damned stupid, under identical quality hardware, both MAC and PC are just as powerful and just as stable. Of course in OSX they haven't cared to program the OS to be able to work very stable on 3rd party hardware which is why gaming on macs is not possible and why macs aren't available in the lower market, but if you have 2k+ to drop on a computer, in terms of power and performance, it just comes down to which OS you prefer and if you want to game with your machine.
Other than that, stability from the actual coding itself is minimal from OS to OS, as I said before on the same hardware setup, XP runs faster, more stable and the drivers tend to work better with less hiccups than on 7. Its just the way it goes though, 7 is the new technology that needs to be refined and the 3rd party hardware vendors need to update their begins to help the OS become more optimized.