Hi,
I'm presuming this the the TV unit you have
http://www.target.com/VIZIO-Class-720p-60Hz-HDTV/dp/B002T9084S
According the specs it has HDMI and PC input but no separate audio input
Vision is no problem using either the HDMI or PC inputs but if you want the audio to go across too, then you will have to use the HDMI connection (HDMI inputs are vision and audio combined in the same cable).
The Mini DisplayPort (vision) on your model Mac does not carry the audio through that port, so you will need to use the Headphone outlet for the audio signal.
Also, the headphone outlet on that Mac also doubles as a digital output for surround sound so you can get 5.1 audio out of that port too with the correct cable.
So you need to find a Mini DisplayPort to HDMI adaptor with audio so you can plug both the outputs of the mac from the Mini DisplayPort and Headphone and then convert them to a HDMI signal.
This is from a site in Australia, but I'm sure you could source one where ever you in world you are.
http://www.macfixit.com.au/shop/index.php?_a=viewProd&productId=1101
This uses the Digital Audio output from the headphone outlet of the Mac and the Mini DisplayPort for the vision and converts it all to a HDMI output for your TV.
Hope this helps
