Question about linux sound...

I've recently installed linux, and so far everything is working great, I
use debian, which makes installing certain things pretty easy, however one
thing I noticed is that anytime I ever want to use sound, I either have to
close any other apps which may use sound, or even sometimes
restart X, otherwise I'll get a /dev/dsp/ is in use error.

I was wondering if this was normal, or if it was actually possible to have
sound come from difference sources simultaneously. I've tried searching
for docs on installing sound modules, with no luck.

PS: I have an AC'97 sound card and use 2.4.27-2-386 kernel on debian.