I have a late 2007 iMac and a vizio TV, the TV has a hdmi and and VGA port on the back. A while ago i decided to buy a mini display port to VGA adapter so i could use the Tv as a second screen. Now i find myself wanting to watch movies and i cant stand the audio still being on the computer while the movie is playing. so i was wondering do i need a cable that connects the headphone jack and the RCA cables (the red and yellow tv cables) on the tv next to the Vga port? or something different.The reason i'm asking is i found myself thinking that if i keep the cables permanently connected then the sound would constantly play/ or not play through there even when the Tv is off. so would i have to specifically choose in settings to play through the built in speakers and vise versa when wanting to play a movie. so that is my quandary sorry for the long rant. just need to know what cable i need.