I guess you just need to research the software you are going to use. I know WinDVD also has an additional DTS plugin for a price. The websites for TT or MP should have codec info.
Edit: You would need to get TheaterTek 2.2 with the Advanced Audio Bundle (
link). Looks like the bundle is $89.95 US while they come in at ~$95 US separately. The AAP gives you DTS and DD-Ex on top of PL, AC3, and DD.
Edit 2: Looks like Media Portal depends on either codecs that come with your video or tuner card or on 3rd party (read: for $$) codecs.