I'm still surprised at how many people say that Vista just doesn't work. I've been using it for over a year, and I haven't had a single problem yet.
I think much of it is expectations. I have XP, and it doesn't hardly freeze up at all other than once in a while. Mostly its just slow.
I had a Mac with OS 9. Granted its not the new X platform, but it still had issues. If you try to open up 20 things at the same time like I do, you're gonna run into memory problems in Vista, OS X, and Linux. Most of these issues people have could probably be more easily solved with hardware upgrades than anything else. But yet, people go and get a whole new computer. Oh well...
Truthfully, I feel the whole debate is totally overplayed. It REALLY doesn't matter which one you get, as long as you can do what you want with it. People throw around a lot of "facts" to help determine which one is better, but in the end there's some good parts and bad parts to all three. And despite what some may say, if you're familiar with one system, you're probably going to like it more. For example, I think Macs are cool looking, and my artistic side likes them, but I can't stand how when you "X" out of a program, it doesn't close. I also can't stand how when you maximize a window, it doesn't automatically take up the whole screen. In XP, I hate how everything runs as slow as molasses, and I have a few virus/spyware threat on my computer every time I run a scan. With Linux, it was hard to find good information on it. There are so many versions that making books for the GUIs is more difficult.