Most businesses I work with are now moving to Windows 7 after skipping Vista entirely.
Strangely enough, Windows 3.1 sure seems a lot smaller and snappier than Windows 7...
I also used Vista for 3 years, and recently moved to 7. It boots much quicker and uses less resources on a consistent basis.
Of course I realize that the plural of anecdote is not data but I haven't heard anyone contradict what I said.
Vista is what drove me to Mac OS, Windows 7 does not seem like much of an improvement in my limited testing. I hated the fact that Microsoft would just move everything around for no good reason, so I had to relearn to do everything I could do in XP. I managed with Dos v3.3 -> XP.
I switched over to win7 on the same laptop and they gave me 4GB or ram. Using the same software, the system lagged so much I had to go back and upgrade to 6GB of ram just to get the PC running at the xp-level of performance.
I also haven't ran XP with less than 2gb of ram since 2005, so I don't know what kind of slowdown xp experiences under resource constraints.
But my perceived performance equilibrium was about 2gb with xp to 6gb with win7.
6GB sounds excessive for that situation, but if your IGP is getting testy about system memory, it seems likely that it'd require a hell of a lot to simulate decent behavior.
(Typed on my Toshiba Win7 netbook, with a 1.6GHz Atom, 1GB of RAM, and Aero running without a hitch.)
Also, I am glad they implemented it. It gives people who just click things, like my girlfriend, pause. It makes them double check what is happening.