Is there a way to separate the sounds totally so the sound is coming from the surrounds is NOT heard the the front speakers?
Yes. Just pan the sound to the surround position. If you are using a decoder then you are limited to the quality of the decoder (and components). Also phase and amplitude errors can play havoc in surround sound. The input impedance of the decoder might not match that of the sound card or the cable connecting the two may be of a low quality.