The name's grown on me since the rumours started yesterday, and I'm happy with the overall design and context of the name and logo in the video. Purely to shake it up a bit, I'd have tried to get a "-tron" postfix in there, as a "Vistatron" sounds pretty cool, in a Transformers sort of way (er, although all the *trons I can remember offhand (Galvatron, Megatron) were decepticon leaders, so possibly not quite the effect we're looking for).
Drawing on many years of marketing experience*, I wonder if this name won't become the Rambo of the software world.
As you can see from the link above, the first movie to feature John Rambo was First Blood. When they made the sequel, they called it Rambo: First Blood Part II. As I recall, Rambo was a blockbuster in every sense, whereas the prequel was just about some guy in the woods shooting people. (I was something like 7 at the time, so my memory of it isn't so good).
When the sequel to Rambo rolled around, they didn't simply call it Rambo 2, ohhh no. That would be too obvious. This was Rambo III. Sure, technically it was First Blood III, but if Rambo was First Blood II, surely that made it Rambo II? "First Blood" was gone from the title, forgotten.
In Windows terms, the letters NT got us all the way to 4.0 (oddly, in 4 releases) before the letters disappeared from the name in Windows 2000. Different letters were used for XP in 2001, but then numbers reasserted themselves for 2003. The letters "NT" are just part of a fading memory.
Sooo... That's my bet for Vista. Sure, Windows Vista might have the Windows prefix for now, but if it's wildly successful, perhaps the Windows name will be replaced with Vista, so the next version will simply be "Vista 2008" or similar. (Or "Vista XP" if we're on another letter fetish at the time).
Alternatively, I'd like to suggest that the Operating System Following Vista be known as Windows: First Blood, just to keep everything balanced and coherent.