For the money these speakers rock. I have a set.
I never had any issues with these guys
I am assuming that you have a good sound card like a Sound Blaster Audigy 24bit that supports DTS and THX, if you do then you will want to purchase something like this. ( This is for visual purpose )
1/8" (3.5mm) mini plug to phone plug is need to run from your sound card (1/8" mini plug out) to the Logitech control hub ( phone plug - which is like a coaxial in ) in order for you to use the sound decoder in the Logitech hub. Once everything is setup you will be able to change in your sound card options between the sound decoder on the sound card and the sound decoder in the logitech control hub. This will enable you to use the DTS and THX features properly. Now all you need is PowerDvD and you should be able to rock you socks off watching movies.