Controlling audio card

Before diving into SDL on WinXP, can someone tell me, to what extent can I control the audio card with it? I want to be sure that only my app’s audio comes out, and none from any other apps running concurrently, for as long as my app is running. I also want to be sure of no delays greater than 20 ms.

If not, what can anyone suggest I use to achieve these goals?

Roger Noss