You were perfectly clear. It seems as though yor problem stems from the fact that you don't have surround equipment, more on that later. Moderm movies are usually presented in 5.1 Dolby Digital from Satellite TV, especially when viewing an HD channel. Unfortunately for you, you have a simple stereo setup with your current system. This means that the two speakers in your TV are trying to reproduce the sound that was intended for 6 speakers. There are more speakers dedicated for surround and background effects than dialogue.
You have several options at hand. One, look into the settings on your HD-DVR. There might be an option regarding audio and you may be able to set it up to only output in stereo. If there is no option, you are SOL with your current equipment. Which leads to option two: get a separate audio sytem from your TV. It doesn't have to be surround sound, as dedicated speakers can create a better sense of depth than TV speakers, so there will be a great deal more intelligability in the sound, but not quite like surround sound. In most modern receivers, there are digital inputs at your disposal, which dramatically increase the clarity of the sound over your current setup. The sound will be good, just not quite as exciin as surround sound, but bearable.
Your third option is t purchase a full surround sound system. Keep in mind that the right system for your room is none of these: 1. The Biggest one you can get; 2. The cheapest one you can get; 3. a BOSE system. Choosing the correct surround solution for your room is complex, but a correctly built system can provide a lifetime of enjoyment. Be sure to select a receiver that is capable of future A/V formats, even if you don't have those formats yet (i.e 1080p/24hz, upscaling and processing, HDMI support, DTS-HDma, etc...). This will allow your system to be up-to-date as long as possible. My favourite A/V receivers come from Yamaha, Denon, Rotel, and Classe (listed from least expensive to most expensive). My suggestion would be to check out one of those first. Your speaker selection will commence from there (favored brands are B&W, Totem Acoustic, JBL). From there, simply choose power solution (Monster Power, or Richard Gray's Power Company), and cabling (Monster cable, Analysis-Plus). Easy enough? Maybe not.
In response to what you said regarding PC systems versus HT systems I say this: Wattage does not equal loudness. In fact, wattage is rated differently amoung manufacturers and should not be a determining factor when mking your sound system purchase. PC sound systems are designed for PC spaces, small offices at largest. HT systems are designed for the smallest of spaces to the largest of rooms, how loud it goes is up to you. And compared to HT systems, PC systems sound lik junk, give no definition whatsoever, and have reliability issues.
I hope this helps, and please take a look at the brands I have suggested above, they have never let me down and they stand behind their product.