Both of the two popular voice chat programs I know (Vent and TS) have their own controls for volume.
Game would be set by the master volume (as well as in game settings, most games do. Even the cheap ones you see on the bargain rack)
Music is set by it's own volume. I'll test it again later, but in my experiences it is seperate from the master volume. Edit: tested on my sister's laptop with iTunes and WMP. Neither changed the sliders in Volume Control, both played at their set volumes. (Play in WMP, set volume low, stop. Start playing in iTunes, (iTunes volume is max), Song is heard at max, stopped iTunes. Back to WMP, heard music at the low setting.)
Voice chat, again, is controlled by it's own volume control.
Furthermore, if you don't like getting blasted by the AIM sounds, turn them off. It's not necessary. Only a distraction to gaming as I see it.