I've been going through mine and can't figure out how to turn it off.
I found the wav file for it (windows ding.wav) and changed its name so windows couldn't play it but instead it switched to a nasty buzzer sound that was way worse than the ding.
It's strange that individual sounds can be turned off in XP but not vista.
I think what you can do however is record a small wav with no sound, name it "windows ding.wav" and replace the original with it.
Sam
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