I think jumping on vista prior to the release of at least the first full service pack will be folly.
imho, I don't see how or why the release of Vista will be any different from the retail releases of previous M$ operating systems. ie:broken.
I personally will not buy the first release. I need to actually use my machine, I have more interesting things to do than beta test retail software. I may consider the upgrade after the release of Vista SP1.
From what I have read of the reviews of RC1 of Vista, it leaves me unimpressed. There are more bells and whistles and petty prettiness, a little more functionality which fits the m$ MO of lets lock out third parties by bundling inferior tools and utilities into the OS. Then there is another layer of obscurity which separates the user from the details of what the OS is actually doing. Are m$ going to apply the same mickey mouse, disney like, patronising default GUI to vista I wonder?
m$ release beta quality software wrt to OSes, they have done since Windows 3.0 I see vista being no different.
To be honest setting up Vista on VMware then attacking/exploiting it will be much more fun than actually trying to use it as an operating system.