Im suprised to be saying this, but Im actually impressed with Win7. It seems to be more responsive at "General use" tasks IE flipping back and forth between programs and that sort of thing. Not to mention all the games Ive tried on it have actually run at a decent FPS boost. Granted, I havent tried anything older than a few years, but so far Ive had no problems with the system.
Which is an almost reversal of my experience with Vista when it was released. My dads laptop crapped out and humorously co-incided with Vistas release. So of course every single machine for sale at the box stores was preloaded with Vista, no choice in the matter. After tinkering around with it, grousing at its drag-ass performance and tendancy to hardlock whenever he plugged in his iPod, I upgraded the damn thing to XP. Of course even that was a chore, considering the laptop manufacturer had hilariously removed XP drivers from their website because "We just expect everyone to be running Vista" as a customer service drone told me.
But oddly enough, after setting up 7 on my desktop after toying with it on a spare machine, Im a bit shocked. The folks comparing the Vista/7 releases to ME/2000 are dead on.
Granted, if you run XP and it works just fine, why bother? But in my experience 7 at least isnt a pile of Vista.