Not sure if it's true, but I would bet that it is. If Vista wasn't compatible, then that would be a major blow to Windows users. M$ can't afford to not have backwards compatibility anymore with such a huge user base.
I predict Vista is going to be similar to Mac OS 10.0. It's basically a complete new rewrite of the OS. I've heard it's slow though, so they're basically not going for speed optimizations now, but that will come later. I'm looking forward to trying Vista out and seeing how it compares.
Hopefully my university will give me a free version like they did with WinXP Pro
