Ok, being the computer dork that I am, I have to throw my hat in here.
First off, I don't own a copy of Vista, aka Mac OS X vB (if you don't think Mickeysoft stole ideas from Apple on this one, check this out:
http://www.youtube.com/watch?v=QT6YO30GhmQ
It's pretty funny, and illustrates my point as well!) I've tinkered with it a bit in stores, and it does look a lot nicer than XP. Of course, all that slickness will put the hurt on your system's resources, as has been mentioned. This is why Vista, unlike previous versions of Windoze, requires that you have a dedicated video card. Otherwise, all the power it takes to run all those purdy graphics would slow your PC from crawl to stop. I've heard though that Vista runs better than XP on the same box. Again, I haven't tried this myself.
On my PC, which I haven't booted up in almost a year, I run XP Pro and Linux. Yes, I am a Mac guy. I keep the PC around just in case I need to run something like AutoCAD, or for the odd bit of gaming I might want to do. I was in the habit of about twice a year doing a 'nuke and pave' (delete Windoze partition, recreate, and reinstall the OS) because the computer invariably slowed down too much for me, and running defrags didn't help enough. It's worth mentioning that I had no tolerance for system performance degradation, thus the blasting of the PC. I also ran XP with most of the slickness turned off - I made it look like Win 2K, and it helped speed things up.
As far as Linux goes, it is something I like to tinker with from time to time, but lets face it - OSX is Unix-based, like Linux. It is VERY stable, and I can run most of the same commands from a command line if I wanted to. I can also run X-apps under X-windows if I want to. I even hear that a lot of the big-time Linux geeks are going over to Macs for these very reasons. So why mess with an OS that, quite frankly, you need to be at least a little bit of a C programmer to fully appreciate (Unix, which Linux is based on, was originally written by C programmers, and the commands and syntax reflect this heavily)? I don't know jack about programming, and I doubt I ever will.
Which leads me to the reason I finally had it with XP, and started using my Power Mac G5 full-time. Securty. My XP box is probably the most stable MS box I've ever used. That's not saying all that much, but I'll give credit where it's due - XP Pro runs better than 98 ever did. What it still fails in is the ability to surf the net with near impunity. I know better than to click at will on emails and attachments while in the MS OS environment, but it seems like if your computer is even connected to the net, you'll pick up some form of spyware. Not a problem with Macs. Yes, there are firewalls and anti-spyware apps you can run, but there is ALWAYS something that WILL get through eventually. Hackers/crackers are smart - they will find the loopholes.
I know it sounds like I'm totally bashing Microshaft, but I'm not. I think they're moving in the right direction by getting rid of some 'legacy' support. Those old, buggy, and largely unused drivers cause nothing but problems, and bloat your OS to boot. People complain about having to upgrade, but you know what? Deal with it! When I was doing tech support back in '99, I got calls from people who were still using WINDOWS 3.1 (Windows 95's predecessor, which came out in the mid-'80s) ON A 386!!!!! That is completely ridiculous, especially considering how cheap new computers are! And lets face it, most people don't need the top-of-the-line PC. They just surf the net and type emails, so these $500 PCs are just fine for them. Oh, and on the Mac side, you can get a Mac Mini for a bit more than that, and it's fine for the same purposes, if not better due to the security of Mac OS. Plus, it's smaller than the average textbook! Don't look for workstation-class performance and upgradability though - it's a bit limited in that respect.
One of the reasons that Macs are so stable is that Apple controls both the hardware AND the OS, so they can write better drivers for their stuff! They even write the drivers for some 3rd party hardware (nVidia's Mac graphics cards come to mind). They also wrote the drivers to use when you install Windows on your Intel-based Mac, which is why I keep hearing how much better Windows runs on Apple computers! If MS stopped supporting so much old hardware and software, I bet a lot of the stability problems would disappear, probably some of the security ones too. The other thing, and I don't know exactly how this works, is that Macs seem to be able to use just about any hardware you plug into it in some capacity, no driver install needed. Like I said, I don't know exactly how that works, but if MS is going to copy Mac OS, shouldn't they try to get the really helpful stuff in there, not just the slick look? I have to say, that pen drive thing is a pretty cool idea. My only concern with that one is that the USB port can't transfer data as fast as modern memory busses, so it'd help, just not nearly as much as throwing the equvalent amount of dedicated memory into your system!
One last axe to grind - MS needs to give it up in the copy-protection department. I'd wager that most people get a new OS by getting a new computer that comes with it pre-installed, which kind of precludes piracy in most cases, unless they want to put an older OS in there, which probably isn't even sold anymore! The 'product activation' is nothing but a pain. Like Gate$ needs any more money. That's like saying the oil companies are near-bankruptcy.
Ok, this has become a novel, so I'll cut out here! Sorry if it was a bit of a thread hijack! :HJ
Joe