Vista seems to be slightly peppier than XP, oddly enough. It boots up in less than half the time; the tradeoff is that the shutdown takes twice as long. Suspend, unsuspend, and hibernate/dehibernate have all improved.
Most importantly, pen support has dramatically improved. The most useful new feature it has is the simplest one: "pen flicks", the Tablet equivalent of mouse gestures, giving me page-up/page-down and editing shortcuts. Automatically switching cursors to show that it's responding to the pen, an animation when a tap or double-tap is received, and another mark to indicate that that the pen button (for right-click) is active. It sounds subtle, but it increases usability a good bit! More importantly, pen response is just plain tighter, and I don't have to intentionaly lie to the callibration system anymore to make it callibrate correctly, since the targets have been moved in slightly from the margin of the screen, where my digitizer always reports the pen position somewhat inaccurately.
If I shove one of my assorted jump drives in the computer and tell it to use it as a ReadyBoost device, the computer becomes notably faster than it was under XP. I fully admit I'm not sure exactly what ReadyBoost is doing, and I know it'll make the lifespan of that jump drive plummet, but it's remarkably effective!
Back to homework now...