Having used Windows 3.1, 95, 98, NT, XP and Mac OS 9 and 10 extensively, I think I'm well qualified on this one. This weekend I installed Windows XP Home Edition (upgrade) on my Sister's PC. Her husband had bought her a digital camera for her birthday, but it wouldn't work with the Windows 98 installed on her PC (it required at least Windows 98 SE) and an attempt to install the drivers on her PC had screwed up her Windows 98 installation. Typical Windows.
I decided to wipe the hard disk. I had to install Windows 98 again since XP was an upgrade, then installed XP. It went OK. Of course then I had to install dozens of critical updates and patches which took hours over dial-up. While this was happening I apparently picked up some spyware (I had decided to download some free programs to check this). I got rid of these and downloaded and installed free antivirus and firewall. When I had eventually finished I though I'd check to see in Windows Media Player 9 would play a DVD. Of course it didn't; it requires a decoder which isn't installed by default (go figure - Macs don't have this problem). I had to purchase WinDVD for $20. That didn't work either. After several hours I gave up (DVDs played fine on Windows 98).
Mac OS just works, plain and simple.