I have no dought that their will be very good music to NWN. But will we be able to have our own music too?

In you own mod of course you can have your own music ;). If they use MP3 or something like that in the game it shouldn't be a problem to replace the sound files. I remember they've said you can use your own graphic textures in the game, so why not music?

Yes, they definately said DMs can add their own music.

:DRSW dances to Sand Storm Remix while beheading some nasty goblins:

Thanks guys. Just wondered. I get tired of the same old stuff all the time.