Update: Having said all that, I came across an interesting thread in another community:
https/community.sony.com/t5/Television-Picture-Sound/How-to-get-5-1-audio-out-from-Sony-Bravia-32-EX-310/td-p/191303
I don't think your TV (and I am not sure how recent your TV is) is capable of producing 5.1 sound. For a DTS decoder to work, the source audio should be 5.1. If your TV's audio is not 5.1 (I am quite sure), then all you will get from a DTS decoder is 2 channel sound.
The best way to achieve this, in my opinion and experience, is to have the audio come from a source that is capable of providing 5.1 audio. For instance, some DVD players have 5.1 decoders built in and all you need to do is to wire it with your 5.1 home theatre speakers.
Simply connecting your HDMI cable from the laptop to the TV is not the solution to get the 5.1 audio experience. That is because your TV might not be capable of decoding 5.1 audio.
If you want to connect your laptop to the TV and want to have a 5.1 experience, then here's what you need at a minimum:
1. Connect your laptop to your TV using a HDMI cable. You seem to have already done, so that's fine.
2. Get yourself a USB sound card. My best bet is the Asus Xonar U7.
3. Connect the USB sound card to the laptop and configure it. From the USB sound card, connect a cable (digital / direct to front, rear, centre input sockets) to your home theatre. A simple home theatre system will do. I have an old Philips SP 100 and it works perfectly.
Let me know what you think.