There's a pretty lenghty thread that covers some of this in the Video forum of all places. I haven't used Azalia sound myself, but I have had X-Fi problems. I don't think they're only related to Vista, mostly with my board/NV chipset, but there's also quite a few Vista users in that thread that are running their X-Fi without issues. Personally, I don't know if the X-Fi is enough improvement over anything else to justify dealing with any potential problems. EAX and overall sound quality just suck in Vista even with OpenAL support.