When will everyone grow up?
Why all these stupid, endless pointless "my OS is better than your OS"? Do you think that anyone will change their positions because of what you say?
Here's my experience with Vista (I have limited experience of Macs and enough of Linux to say "nice try, might be ready for mass market in a few years").
I read the horror stories and went ahead anyway. The only driver I got in advance was for my NIC as with a network connection, I could fix anything.
The upgrade itself was flawless and painless. I didn't count the number of times I interacted with setup but it was a small number (product ID, keyboard and region and timezone I think). My TV tuner and graphics cards didn't work, which I expected, but installing the latest drivers brought them on line. Since then, I've had no problems at all, zero. It "just works". As to aesthetics, and of course this will always be subjective, it is at least as good looking at OS X. The performance is great, even with 512MB of RAM on the box I upgraded (and yes, that's with Aero). It's also easy to use. Certainly, my folks, who know not one word technical, will be able to use Vista with ease.
Now of course, we could get into some feature by feature p*ssing competition but what's the point? Vista does what I need, without hassle. Will I continue to buy MS? Well, why woudn't I?
Finally, regarding security, I don't believe Macs or Linux are invincible, in fact I believe the number of exploits discovered is proportional to the installed base size, but I practice safe computing. I don't use an admin account for my everyday work. I use anti-malware software, a good firewall and a lot of common sense. And just like the guy in the Mac ads, I don't get viruses or other malware. I wait with mild amusement for the inevitable down to earth bump that so many people will get when their own particular flavour of invincible OS connected to a network becomes the target of some shysters attention.
If you love Mac, then good on ya. If you love Linux, then good on ya. I love Windows, good on me.
PS. I am very technical, I'm not stupid, I've been in IT for 20 years covering most roles and I make a concious decision to stick with Windows. Enjoy your technology folks.