Posting this from the Microsoft PDC Windows 7 preview build. Which is not very different at all from Vista, in fact. A few UI tweaks here and there, the Windows Explorer layout is improved; there's a new thing called Libraries which aggregates multiple folders into a single view, which is quite cool. Wordpad and Paint have Ribbon interfaces.
According to MS, it's got full driver compatibility with Vista. I'm running it in a virtual PC, so I can't really tell.
Also just been watching a demo of Office 14 (on Channel9), which looks
really cool. There's a browser-based version which uses Silverlight if you've got it, AJAX if you haven't, and it's cross-platform. That includes Word, Excel, Powerpoint and OneNote. If you've got a document stored in SharePoint or on Office Live, you can have multiple people editing it at the same time from the full smart client, the web client and the Windows Mobile client, getting live updates from each other. The browser Excel has the same calculation engine as the full smart client Excel.
EDITED: 7 Jan 2009 13:42 by RENDLE