I am trying to connect a dell laptop to a sony tv via a hdmi cable, but I don't get any sound on the tv. I am running widows 7 on the laptop. I don't get an option to set hdmi as sound default
Right click on the speaker icon down by the clock (on the computer), Select playback devices, click once on HDMI audio out (or something similar) to highlight it, then click on the "Set Default" button under the list of playback devices.
You may need to set it back to the speakers (or whatever it's currently on) after you disconnect the HDMI cable.
The first thing I'd suggest is making sure you have the latest video drivers installed, you may have either an AMD video chip or an intel chip in that so check and select the correct driver