Vista is horrible - your components may not be low end, but the OS is awful.
I'm saving up to build a PC for myself, but will wait till 7 is ready to launch.
That's why my PC runs Windows 7 beta, and XP 64 bit professional when 7 just doesn't cut it.
If you know your way around, you can definitely be just at productive as an OS X user. It's just loud, I have to diagnose problems myself, and I have like ten different warranties to deal with. On the upside, I spent less than the mid range iMac and got a much more functional computer.
Stories like these are everywhere. People are just different and have different needs. In the end, we're just fighting over a product. I don't really like the Microsoft ads, they leave a lot out. But so did the Apple ones in the recent years. I mean, go back and watch all of them.