vista
I really wanted to give it a shot. I really did. It pained me to see so many people talk about how Windows Vista sucked before ever using it. Microsoft ran the Mojave Experiment, where a bunch of Vista-bashers were forced to use the new operating system "Project Mojave". Almost all of the users told researchers that the new OS, actually Windows Vista with no modifications, was in fact... good. Of course, when I got my new Dell XPS M1530, I allowed myself to use Windows Vista Ultimate Edition.
Short version of the story: it sucked. Hard.
Long version: The first impression and the out of the box experience are the most important things a product has to give a customer. A laptop, which is supposed to be portable, absolutely must have wireless networking. In the year 2008, there is no excuse not to. I ordered the Intel 3945ABG card, expecting to dual boot Ubuntu. Windows Vista doesn't support WPA by default. Even with SP1 installed from the factory, I still had to go on a Google run to find the hotfix. Also, wireless as a whole was just the cruddiest experience I've ever had. ndiswrapper was more fun than working with wireless in Vista. The Intel card has open source drivers in Linux; how in the world can Vista not make it work? It turns out that the default drivers included with the installation just hates wireless networks. Don't believe me? Google up "3945 vista". And no, this isn't an isolated case. My dad's laptop, which has a 4965AGN, suffers from the same problem. It just so happens that every card iwlwifi supports dies in Vista.
Not only does Vista have some hardware support problems (and I mean with recent hardware too!), but it also is a total resource hog. Windows Vista was designed to almost require 1GB RAM just to run acceptably. An installation requires at least 15GB of hard drive space. The fancy Aero interface takes even more horsepower on top of that. This translates directly to a noticeably slower experience on the computer.
And finally, Vista is killing its older sibling XP in order to take its throne at the top of all operating systems. New computers that are "Designed for Windows Vista" (as if, considering the woes I had and the class-action lawsuit) are not in any way obligated to support Windows XP. My laptop blue-screens everytime I try to install Windows XP. It just won't work. Dell tech support is ever-so-helpful, telling me that they won't help me install Windows XP whatsoever, and that if I got it working, I basically gave up all rights to any tech support in the future.</sarcasm>
In conclusion, Windows Vista sucks. Whenever you tell a friend that it sucks, you can feel proud knowing that there is actually a user out there who gave it a shot. It still sucked.
Update: I'm testing out the Windows 7 Beta, and there's a lot to like about it. But then again, only time can tell what will happen to it. Personally, I think the main weakness of Microsoft and Windows is the gigantic user base. Every version of Windows has to keep up backwards compatibility with programs that ran on its predecessors. It's a shame that Microsoft can do an OS X-esque refresh of the entire Windows operating system, because too many people depend on Windows. My suggestion? Branch Windows into a legacy line and a new line, and try to gently transition from one to the other.