DISCLAIMER: If you're a fan of the mac, you probably shouldn't read the following. It is admittedly heavily biased, as I have even stronger than usual feelings about Macintosh in general.
I'm going to stick with Windows. For two reasons:
1.) I want to be able to do something other than photoshop and iTunes
2.) I kind of feel like there has to be a good reason why the mac took more than a dozen tries at their OS before finally scrapping it for this new OSX action.
OSX is great, don't get me wrong, and basing it off of Unix was a very smart decision from what I can figure...but it just makes me gape in awe sometimes that they've been through so many different incarnations of their operating system and it took them until 2005 to figure out "Maybe we should make it so you can quit a program when it crashes instead of locking up the whole computer and requiring you to yank the plug out to turn it off" or "Maybe we should have higher speed ports for the peripherals and lower the interrupt requests on these USBs so that the mouse and keyboard don't randomly die," etc.
In the newspaper business, I have a lot of personal experience with Macs, all the way up to OSX/G5's, and though OSX is pretty good, I still can't do 1/10th what I can do with Windows (or even Linux, since it at least uses the same file system as Windows, I believe...though I may be wrong). I can't do things like change file extensions because of that stupid ass binary file header table crap, and unless I'm playing like WoW I can pretty much never play anything on it anyway, yet they throw these super jacked video cards in them and crank the price up a grand. I don't want to have to spend $250 bucks on an Airport because it won't like my Windows-favoring router...I don't want to have to fly blind when designing websites because all the mac versions of the browsers have craptacular support for new web specs...and most of all, I don't want to pay $3000 for a computer that looks pretty and can't do anything I want to do.
I agree totally that I wish Microsoft would start a new OS from the ground up, maybe based on open source stuff like Linux, etc., but I guess they are taking an approach where doing tons of extra work for the same result profit-wise is a no-no.
Admittedly I know little of Unix or Linux, but to be honest, I don't think I need to, my feelings about the Mac in general are undoubtedly gonna keep me from swaying.
The bottom line here is that I am very anti-Macintosh; I always have been. There are decisions made for Macs that just seem to me like Jobs wanted to proprietize and screw Windows over; unfortunately, as we've all seen, it went the other way, because Gates got more of a hold on things early on. Now the two are comparable and in many/most cases, the Mac is actually better...but that doesn't stem my absolute hatred of them. So unfortunately I don't really care how good or allegedly stable the operating system is, or even what great systems its based off of...I'll be going Windows Vista, simply because OSX is mac, and I will never ever find a place for a mac on my computer desk, no matter how good it is.