My favorite part is where they threw it all out, reset to 2003 codebase, and started from scratch basically, 18ish months before release.[1]

So from a technical standpoint, Vista took longer [5 years] and had less development time [under 2 years] actually make it into the product. (Yes, code they already had they could and did reincorporate into the final product, but still, wow.)

[1] http://blogs.msdn.com/b/michkap/archive/2005/10/16/481625.as...

This post is full of snark by the way, but it is useful to know what went wrong with Vista. (TL;DR: Management of very large software development is _hard_)