The noise is, I think, the default beep for windows 7. It should not be affecting you as much as it seems. Open the Control panel (Icon view). Click on the "Sound" icon.and then the "Sound" tab.
In the "sound schemes" window, you have a string of choices. The default should be, in fact, "Windows Default" (unbelievable eh- lol). You can change this window to any of the given schemes. But this may not be a solution to your problems.- it will only change the sound you can here!.
If you scroll down the list in the lower panel, to "Default beep" (I think this is the one that is troubling you) you can turn it off entirely, or select any og the other sounds shown, as it's own default sound. You will see at the bottom...