Okay, have isolated the crashing issue (with Menty's help, sorta) to a conflict between Vista and the Creative driver for my Audigy 2 ZS. Got an updated driver from Creative that lets the new OS use the sound-card without crashes, but its support for 5.1 speaker configurations (which is what mine is) is negligible. I can select 5.1, but only the center, front left, front right and subwoofer produce sound -- rear left and rear right are absent.
But since I'm not even THINKING of trying any gaming via XP emulation, that's not a dealbreaker right now.
A couple other bugs -- my webcam isn't entirely supported. I can see video from someone else's cam in Live Messenger, and audio is perfect sending and receiving -- but my vid is scrambled.
One last one -- Vista-native IE 7 has a bug where if you go full-screen, the "Favorites" button stops working. The XP version of IE 7 does not have this problem.