If you like the older look then go with Window's 2000. But personaly, I would go with Window's XP. It has a unique interface (It's a common interface but unique) and it runs very smoothly. It doesn't have driver problems like Window's Vista does. I mean, don't get me wrong, Vista is a pretty OS but, has some bugs in it. I wouldn't want to run it on my notebook or desktop until they fix the bugs in SP2. So my advice is stick with the common Window's XP for a while.
Windows Vista is pretty awesome. But, I have had to use System Restore 2-3 in the last few months. Word from the wise, don't download things from the depths of the intarwebz.
I don't agree with this statement. Too simple.
People in average doesn't know much about OS.
Maybe they need to know what is best for them.
Example = Vista is best for kids and homosexual and superficial people (see below).
XP for pro gamer and other professional,
Windows 7 beta for testers ( Dummies ),
Linux for open minded people and that are not gamer,
Mac for those who have extra money for this precious luxury.
Vista if it works best for you
XP if it works best for you
Window 7 beta if it works best for you (but its a beta)
Linux if it works best for you
Mac OSX if it works best for you and you have the money.