the precursor to Longhorn/Vista was in development as early as August 2004!

[chrisNova777]

https://en.wikipedia.org/wiki/Development_of_Windows_Vista#Longhorn_%22D1%22_or_Milestone_8/9

Longhorn "D1" or Milestone 8/9
Build 3790.1232 (build date of August 19, 2004[18]) is notable, as it was the first build of Longhorn based on the Server 2003 code base, but with the Windows XP interface. Successive internal builds over several months gradually integrated a lot of the fundamental work that had been done over the previous three years, but with much stricter rules about what code could be brought into the main builds. Builds in this period of time were described variously as Longhorn "D1",[citation needed] and as Milestone 8 / 9, depending on whether the new or old build tree was being worked on. Evidence of a similar build marked as Build 5000 (built on September 8, 2004) has also been found.[19]

Build 5001 (build date of September 12, 2004) the other Windows Longhorn build also has a Windows XP Interface. The wallpaper is the same as Windows XP, but has a bull with long horns. The boot screen is also the same as Windows XP, but has "lh" replacing "xp". The "lh" represents "Longhorn".

Build 5048 (built on April 1, 2005) was the official WinHEC 2005 preview build, described as the Longhorn Developer Preview, and made available to WinHEC attendees on April 24, 2005. It was the only build from this time period that was made available by Microsoft; it was not officially distributed outside of WinHEC, but the build quickly appeared on file sharing networks. The Aero visual style made its first appearance in this build, and the Desktop Window Manager was present but disabled and hidden by default. At the keynote presentation, Bill Gates also announced that many of the WinFX developer APIs that were originally planned exclusively for Longhorn were going to be backported to Windows XP and Server 2003, and that the final user interface for Longhorn would not be seen for a while longer. Other features such as device-independent resolutions, rasterized icons, virtual folders, and registry virtualization were discussed as well.

Build 5048's closer resemblance to Windows XP than to the prior Longhorn builds from 2003 and 2004 surprised many, leading well-known Windows enthusiast Paul Thurrott to write: "My thoughts are not positive, not positive at all. This is a painful build to have to deal with after a year of waiting, a step back in some ways. I hope Microsoft has surprises up their sleeves. This has the makings of a train wreck."[20] Months later, Thurrott stated that the Vista development process has since recovered in the more recent builds.

Build 5060 (build date of April 17, 2005) No major difference to Build 5048, except it had a new style logon screen. The desktop wallpaper was changed.