Summertop: I would most definitely call it a downgrade rather than an upgrade. All you get at the moment are some additional restrictions and obscure "security advantages" which are so annoying that everybody will ignore them/ turn them off after a short while. This article ("20 Things you won't like about Windows Vista" may be a good start, although I wouldn't agree on some of his statements, especially on his "OS-Ranking". It definitely shows some disadvantages from the user's viewpoint.
Anyway: I have not heard of any reason to switch to Vista except its improved look&feel (which is IMHO inferior to the look&feel of other modern OSes like MacOS or up-to-date Linux distributions) so far.
(Cacher) Jouez une partie en temps réel avec un joueur en ligne! Pour que cela soit possible, vous et votre adversaire devez choisir l'option "Jouer et rester ici" par défaut puis recharger la page avec la touche F5. (TeamBundy) (Montrer toutes les astuces)