that could honestly be a possibility, it could be very likely that all your ram is filling up and some of your cached files such as your audio files could be pushed back into paging files on your hard drive, which would quickly explain why your audio is slow,
was the sound all distorted, before you switched to vista? you may also want to stop all background applications, then attempt to pay whatever if it runs clearly then you may need to get another stick of ram, or downgrade back to whatever was on the computer before hand