Bit the bullet and installed Vista Ultimate RTM as the main OS on my laptop this morning, replacing my aging WinXP installation. Setup went without issues fortunately, and all significant hardware is working right now.
Lots of stuff to install yet, but as of now at least I have the core Office 2007 package installed, though I'm missing Project and Infopath thanks to the product-key screwup in MSDN. I'll wait until the new keys are up before installing and activating them, as I don't feel like going thorugh the phone activation to get this resolved right now. This is precisely the kind of thing that makes me dislike the whole activation affair; it just a bother and doesn't solve anything at all. And if MSDN can't get this right, why expect the rest to be any different?
Also went ahead and installed the Virtual PC 2007 beta. My machines imported OK and seem to work fine even without updating the VM additions to the 2007 version. I'm updating just one of them for now to see how it goes. I did get a scare earlier today right after installing VPC: I tried launching any machine (even a new, empty one) and it would just sit there with a black screen consuming 100% CPU. A restart fixed it, though no idea what triggered it.