crap os still :)
winsxs like uac and the rest is just another layer of plaster on top of a rotten limb. For the same reason you decided to toss your network, MS must toss its trashy OS foundations, and I am nor optimistic. I envy you for being excited by a MS initiative, so I will look into about W8 (thx for the link), just in case I can share the excitement. As far as I am concerned, the last excellent thing coming out of redmond was midtown madness.
Also, don't be put off (you don't seem to be) by some commenters' after-the-facts "easy to avoid" advice, or stupidly, their contempt. Your "By the time you even think about the first project thrown into service at 80% completion, it’s been MONTHS," says it all and the vast majority of us share it.
Side note: That's why IT mostly is NOT engineering. A bridge, a plane, a car or any other machine don't stop at 80% design and test completion. The first 2 typically are 100% completed and verified, the latter not far behind.
On the other hand, except for things like chips and some specific equipment where IT costs are zip compared to the consequences (space, health, military, traffic control, manufacturing machines like your vinyl machine, etc), cheap and good enough is the rule in IT, especially in IT departments (and their suppliers) where IT is a means; Few "engineers" there.