Firstly, mac Hardware:
All the hardware in a mac works perfectly with every other piece of hardware. They're all made to go together, unlike PCs where the parts are made to be as interchangeable as possible. In my experience, there's simply no such thing as a poor quality mac, unless it's a QC anomaly. As for PCs, I'd say at least 50% of them are poor quality, probably considerably more. The speed at which macs run when doing processor-hogging tasks is astounding. As I test I found that if I turn on "Spaces" (up to 16 seperate desktops you can move between to keep things organised) with 4 desktops I can watch a full screen movie in each one at the same time with no noticeable lag. Bit useless to actually do that, but it shows that they run well. The hardware is incredible, and they put it into a beautiful and compact machine. The downside to this is that replacement/upgrade can be a PITA and expensive. But the hardware upgrades aren't nearly as appealing as they are on PCs.
The operating system is tried and tested, it works, works well and is more than rock solid. I've never had my mac reboot on me. I can run it for weeks, more than a month on end without resetting it and it still responds just as well as it ever did. Downsides to the OS is that while it's very flashy and runs extraordinarily well, there is a bit less refinement than windows; for example, there is no simple drawing program on mac that rivals MS Paint. Paintbrush is horrible. Generally things just behave a little bit differently than windows, and it gets a bit annoying. I do miss Windows Explorer, even though it didn't run worth a damn. It is great, though, that on a Mac as long as you have an admin password you can do whatever you want. I got really sick to death of windows telling me I couldn't look at a folder on my own bloody computer
Mac updates are also faster than windows. For me at least, windows took eons to download an update, eons to install it and generally things ran worse afterwords.
Also, mac viruses are practically unheard of compared to windows viruses.
In short: Macs are very fast, very reliable, with great hardware. There can be some compatibility as some software is still unavailable on Mac, but you can still run Windows on an intel mac with Boot Camp.
PCs are generally slow and unreliable (IME) with everything ranging from extremely poor to great hardware. Just about any program can be installed on windows, including every virus under the sun. I expect you would have to pay more than a mac to get a PC of the same quality though I don't know about laptops and macbooks.
Just my thoughts!
Pete