"I dont know where you found this OpenAL information, but it's not true."
right....... OpenAL and Windows Vista
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DirectSound - Wikipedia, the free encyclopedia
"Because of Xbox and Windows Vista integration, Microsoft is actively pushing developers to migrate new applications to XACT. As a result of this, Windows Vista runs DirectSound in emulation mode on the Microsoft software mixer. The emulator does not have hardware abstraction, so there is no hardware DirectSound acceleration, meaning hardware and software relying on DirectSound acceleration will have degraded performance. In the case of hardware 3D audio effects, they will not be playable."
simply, vista forces most audio through SOFTWARE MODE and will not be able to use hardware accelerated functionality that the soundcard provides, the exception is as you know kingaustin, OpenAL applications.
It is nice to know however, that you didn't notice a degradation in sound quality on vista, whether the program used openal or not.