Good choice!

I have been running the Vista Ultimate RTM for a month or so and I am yet to break it!! Sure, there are some software incompatibilities but these will disappear pretty soon, as software houses start to cater for the Vista market.
As to the release date, I can find nothing concrete. At least you have ordered it and will, more than likely, have it on your PC before the end of Feb! I know you'll love it.