Missing the point
Several of you here are missing the point about Linux on the desktop. First, having thousands of apps available doesn't mean you're going to have J. Random Worker installing them on his work computer any more than having thousands of apps for Windows means they'll end up on your LAN because you can lock Linux down just as well as you can Windows. What it means is, you'll probably find that most of your software needs are filled without having to write custom apps.
Second, if you think there's lots of retraining needed for Linux, you've either never used it or you're on the left side of the bell curve. You run Linux from a GUI, just as you do Windows. You use a mouse, you use double-click to open files and right-click to reach a context menu, exactly the same way. And, up at the top of every program you find File, Edit, View and so on, just like you're used to.
My sister is a Windows refugee, now running Ubuntu. I do her tech support, and I can assure you that she needs no more help now, than before she came away from the dark side. Not only that, most of what she needs is OS independent: problems with a website, finding a "lost" file and so on. It's been months since I had to help her with anything Linux specific. On a day-to-day basis, It Just Works.
Last, and especially with the economy as bad as it is now, there's the argument that by switching to Linux instead of upgrading Windows, you're not only saving the cost of upgrading now, you're saving the cost of every, single, future upgrade of Windows, along with no longer needing to pay for (or use) anti-virus software.
Yes, I'm a Linux advocate, but I'm not a fanatic. If you like Windows, and it does what you want, the way you like it, go for it. I'll continue using Linux, TYVM, not only because it does what I want the way I like it, but because it's free. Free as in beer, and when you're as broke as I am, that's quite an important consideration.