The problem is, it retains a lot of WinXP's faults: The menus, the folders, the menus, the base Windows code, oh, and did I mention the menus? Sure, Vista is sorta pretty and fluid-like, with windows expanding and collapsing in a very Apple-esque way, but there's no testament to its solidity. Will it crash as often as any of the previous iterations did? Unfortunately there's no real information yet. Vista was released to corporate customers back in November, and there hasn't been a lot of news either way.
There was news from hackers, of course, who found major back doors to Windows security as recently as, oh, look, today!
As a Mac and Windows user, my disdain for using Windows has only grown since Apple released OS X 5 years ago. Its beauty, fluidity and solidity have earned it a place in my will (seriously, I am donating money to Apple when I die.). The OS simply works, probably in part due to its Unix core. Solid functionality all the way, even it isn't entirely enterprise friendly.
I remember when Windows 95 first came out, it was being called Mac OS 86, as it called upon the most important features of that ancient OS and rebranded them with the Windows logo and attempted to pass the whole package off as a brand new operating system. Still, it was leaps and bounds better than Windows 3.x, though the Blue Screen of Death was a nice carry-over.
Here we are 12 years later, and Microsoft is pulling the same schtick. It's leaving the real innovation up to its competitors and is leveraging that knowledge in its own products. That's right, Vista is Mac OS X 2001, not-so-cleverly disguised as a wholly different OS.
The bottom line for enterprises that are interested in upgrading to the new system is to take the wait-and-see approach.