Windows CE is the worst, you can't boot safe mode on that rubbish.
Windows vista is good, not sure why people dislike it, windows xp can't optimize duel cpu's as good as vista, so not sure if you know exactly much about computers.
Windows 7 , umm, don't plan on using it yet, maybe on a new build, from what I've seen on the repairs I do, 7 isn't to bad but it is full of useless applications and widgets, altho they can be taken of quite easy.