Longhorn wasn't the codename for Vista - that was a lie we told to cover the truth :) Longhorn was a massively ambitious upgrade to Windows XP that had a whole new relational DB file system (WinFS), managed memory graphics stack comparable to Flash (Avalon), and abstracted network layer (Indigo). The project didn't converge.
In late 2004 we cancelled the project and scrapped all the code we'd written since 2001. We forked Windows Server 2003, and reworked the specs to get the most bang for the buck on a limited time budget. Compromises like using a search index instead of a relational db filesystem, the sidebar was rewritten for the 3rd time, etc. All in all, it was an ok release considering.
In late 2004 we cancelled the project and scrapped all the code we'd written since 2001. We forked Windows Server 2003, and reworked the specs to get the most bang for the buck on a limited time budget. Compromises like using a search index instead of a relational db filesystem, the sidebar was rewritten for the 3rd time, etc. All in all, it was an ok release considering.