For playing DTS format movies, you need a DTS-enabled software like PowerDVDXP and DTS-certified Hardware, otherwise you could still watch the movies but without sound....
I use same hardware as you do, I choose Dolby Digital 5.0 or other sound options besides DTS surround sound to get the sound.


DTS-certified Hardware: DTS certified sound card and speaker....those ones are usually more expensive than their normal counterparts.

Hope this helps.