My Intel-based MacBook dual-boots in OSX and Vista. Honestly, I hardly spend any time on the Vista side, but have been using it more for some Windows-only services. But I shudder every time I go in.
Why? I really can't put my finger on it. Partially it's the fact that the default mouse speed is too fast, so until I adjusted it, the pointer would just careen across the screen. Partially it's because Vista has retained some aspects of previous versions of Windows but updated others, so it feels like a mishmash rather than a well-integrated whole. Partially it's because of all the system noises, which to my ear sound self-promotional and needy. In any case, booting into Vista is like picking up a greasy Tupperware dish for me. Yes, I could spend some time washing the thing with lots of soap, but I'd really rather just throw the thing away.
I don't have this reaction with XP, which I regularly use in the labs. Anyone else using Vista? And what is your reaction?