Upgraded to Vista RC2 (build 5744) a few days ago while I was waiting at the airport. Boy what a difference! Speed is improving all the time and the sleep state now actually works on my laptop! Try it out for yourself! Before it would crash trying to resume but now pops pack into life very quickly. Everything seems a lot smoother now and were finally at what I would consider to be close to production quality.
Not long from here folks!