in 1995 I switched from Windows to Linux. Some things were hard at first, because a lot of the niceties of today were nonexistent. StarOffice was written in Java and it was crap. No presentation software to speak of, etc. But understanding what my system was doing made my life a lot easier, and this is something diehard Windows users will never understand - regardless of anything else, it is impossible to know what your Windows computer is doing at any given moment.
I stayed with Linux on my desktop until 2008, when I bought a Mac Pro. This is an impressive machine even 3 years later: 2 quad xeons, 20 GB RAM, recently upgraded hard drives to 4 2TB in RAID 5 with a RAID controller, 1 30" Mac Display + 2 21" Dells. This made me happy because, even if I was losing some control by going to a proprietary OS, the fact is that the Mac OS X experience is superior to both Windows and Linux with any of the available window managers. Having a GUI that actually works and a real OS underneath (meaning Unix) has allowed me to tinker when I wanted to tinker, without being forced to tinker to get work done.
But them Apple started acting up. First, was the stupid App store on my desktop. Then, Lion took away more than it gave me. And it signals that Mac OS may be going in the direction of turning my desktop into a tablet, which is definitely not what I want. My computer was never a "consumer device," an online shopping machine like what Apple created with the iPad. I bought a laptop 3 months ago, MacBook Pro, just before Lion was released. But I think that this is my last Mac. I'm excited about my next machine, which will be going back to Linux. Both my desktop and laptop still have plenty of life in them, so I'm not contemplating a purchase in the next 2 to 3 years, but check back with me then, and I suspect I will say that my best upgrade ever was going back from Mac to Linux.