Somehow I'm on thin ice here, so I better be a bit careful, because I don't know Vista, just tried it, and even worse: I'm not into gaming

I'm a programmer, and from my point of view: The best OS, the perfect OS, will I ever find it? My programs are geared to a semiprofessional market with lots of text processing. What I need is raw speed and and few font problems as possible, and a very important part: backward compatibility.
One of XP's strength is the last point, backward compatibility, but it is also XP's weakest point. XP is at a point where Microsoft had to make a decision, backward compatibility or not. They decided something in between.
Windows is geared to the consumer marked, office applications and games. As I said, I can not enter your discussion about gaming, but I'm sure Vista is more than good enough for the consumer market.
For myself, I think I'll end up having one XP machine, one Vista and one Linux. For me the best OS is a mix between those three.
grandpa