Microsoft would be making a major mistake cutting backwards compatibility from Windows 7. One of the #1 complaints about Vista is its not backwards compatible enough. I think MS should keep some of the things they did right in Vista, like the Aero interface. They should make it more memory efficient, fix the slow IO problems (its better in SP1 but still not perfect), and overall more budget PC friendly. Most people buy cheap $299 desktop bundles or $399 laptops, and Windows needs to scale down to run acceptable on that type of hardware. I think a large reason Vista is bashed so much is because people expect it to run faster than XP on their cheap laptop with 512MB of RAM, but that just isn't the case.