I've been using a couple of MacbookPros recently, one with Vista installed under Boot Camp and one with it installed under Parallels so I could access it from OSX.

To try and get the best of both worlds I tried to install Parallels on the Boot Camp machine to get it to work with the Boot Camp partition....

No luck getting it worked (the option was un-selectable) to I emailed Parallels support to see if it was an option.

I'd hoped for a work-around, or at least a "coming soon" update.

What I got was less helpful:

Thank you for contacting Parallels support.
Sorry, but we won't provide Vista support with Boot Camp.
Best regards, Sxxxx Rxxxxx.

Pretty sad really. It means I've either got to use an extra Vista licence and run two versions on the machine (with all the associated trouble of remembering what's installed where) or go for one of the two compromises - either have to reboot every time I want to use OSX (and not be able to run and test an IIS hosted Silverlight application in Safari) or only run from Parallels and put up with the performance hit (what's the point of having two cores and only being able to use one of them most of the time)

Now I don't know if the problem with getting this to work lies with Parallels, Apple or Microsoft but it strikes me as being in the interest of at least the first two (and probably Microsoft as well) to get it working.... currently there's no compelling reason to buy a Macbook Pro for me when Toshiba, Lenovo, Dell etc all have better value hardware. That in turn means I don't buy a Parallels licence or get good exposure to OSX

So it looks like, for the time being at least, it's back to using my Vaio for Vista and my rather old (RevA 877Mhz 12") Powerbook for OSX testing.