I have been working with Win 7 for almost 6 months and it is rock solid. They have not added much benefits/features but made it really good and solid.
It is much faster(like XP) but gives you the latest and greatest features of Vista. If you have a new hardware and you are running XP for reliability you will have to move to Win 7.
I know Bert will have a comment on this post. I am a bit biased
Last time I used AC on tablet it was not tablet aware(like writing etc), so what do you use it for?