Without hesitation I must say that Windows newest OS, the mighty Vista, is a pain in my rear end. To preface this, I will disclose that I am a linux user (Since 2002). It doesn't mean that I hate Windows or Microsoft, it's just that I prefer customizing and controlling my computer, as well as the security benefits inherent to Linux. No anti-spyware, anti-virus, or anti-malware software is necessary.
So with that stated, my adventure started when my wife's laptop overheated and literally cracked our glass-top dining-room table in half. It broke off, dropped to the floor and shattered. Along with the laptop. So after a few days of weighing her needs, we decided to get her a super-cheap ($399) laptop from the local Big Box. She only does web browsing, email, some photos, and a bit of genetics work, so the Acer 3610 with the Celeron processor was just fine. Or so I thought. SIMPLY BOOTING INTO WINDOWS VISTA WAS ENOUGH TO BRING THIS COMPUTER TO IT'S KNEES! And this was with all of the eye-candy turned off! Why would you make a computer and then load an OS on it that drains all of its resources?! Anyways, I next decided to remove Norton and install a cheaper anti-virus program. That's when the real fun started. On reboot, I had lost all internet connectivity, and almost every program I launched began to crash. It was a nightmare and I had to do a full system restore to recover. The same thing happened when I tried to install a firewall (as I've heard that the Vista firewall is crap).
The bright side is that I may have made a linux convert out of my wife!