Windows XP is clearly better than Windows Vista.

Vista just has more compatibility issues. It's about the same as XP as an OS -- meh.

Vista is slower with lots more eye candy and annoying UAC. How is it not worse? >=O

My opinions are from personal experiences. I understand that Vista is slower in benchmarks, but I haven't noticed any significant slow-downs on my Vista machines. UAC's annoying but privilege controls in my other setups (OSX, Ubuntu) is annoying as well.

I think that for people who knows how to wrangle and tweak XP, Vista is a huge letdown. But for someone like my mom, the wifey, and friends, Vista is a much better choice for security, "prettiness," etc.

I thought Vistas security was found to be pretty much useless.

Prettiness, yes.

Security, well, if you're carefully watching each prompt and verifying that the action about to be performed is not harmful to your system, yes. If you're like most people, who just end up clicking yes to make the prompt go away, no, it's not more secure.