Vista was the final straw for me with Microsoft products as well. I was part of the club that initially bought into the greatness of Windows 95/98. I didn't know any better back then, really. I made a lot of the same arguments in defense of Windows versus Mac and Linux that I've seen in this thread.
My dissatisfaction with Microsoft didn't begin until my first XP installation, and the third party firewall I always installed (Kerio), which clued me into the evilness of Microsoft's empire. Basically, I ran a file search on my local hard drive. I forget now what I was looking for, but Kerio popped up an alert for outgoing traffic the second I clicked the search button. Seems that Explorer.exe wanted to contact Microsoft servers every time I performed a search, even though the search was limited to the local drive. I permanently blocked that action, but it left a really bad taste in my mouth. MS has no need nor right to be contacted when I am looking for personal files stored on the local drive.
When the abortion that was Windows Vista came out, I switched to Ubuntu, and haven't looked back since. I keep a copy of Windows XP on a small virtual machine with no outside access for the occasional task that requires a Windows OS. Other than that, I have been free of the Microsoft teat for almost four years now. That's not to say that Linux and FOSS don't have their own problems and frustrations, but I'd rather search for a solution on the Ubuntu forums than the Microsoft Knowledge Base any day of the week.
Over the past four years, I have switched all of our corporate servers over to Linux, and am slowly switching workstations over to Linux or Mac, utilizing Windows on locked down VMs wherever it's necessary.
I wish I would have had the foresight to make the switch sooner; I would be just that more experienced with it.