But why June 21, 2006, specifically? According to Wikipedia, there was a circulated Pre-RC1 Vista build (but only the first of 3) that was built on June 20th, and June 21st was the first day of summer that year, but neither of those seem like good reasons to pick this date in particular.
bibinou|9 years ago
Previous beta releases only had a very limited set of drivers.
Microsoft greatly remodeled the driver model in Vista so that's why drivers can't be older than this date.
mnarayan01|9 years ago
Sanddancer|9 years ago
[1] https://en.wikipedia.org/wiki/User-Mode_Driver_Framework