Depends on the capabilities of your un-named components and what your intentions are.
Do you want the TV to be the audio source? As TV's
are not the best sound sources, being designed to just make high-quality flickering visual images
with passable audio accompanyment, this is NOT the optimal way to go, but it is do-able. You know this. Run its RCA audio L and R Outputs to any available RCA AUX Line Level Input on your system.
Do you want to hear TV-related audio on on your audio system? This is HIGHLY recommended as it tasks the specialized audio hardware to deal with the audio while bypassing any handling of the video. You can still run your vanilla analog RCA pairs between Cable Boxes and/or DVD's to the TV if the TV has sufficient audio inputs AND you can run the nice digital audio outputs of those video-producing sources to your HTS, if IT has sufficient digital inputs (*).
>>>> * A word on coaxial vs spdif (optical) audio cabling - I always use coaxial if I have the choice because it is A) cheap RCA cable availabel anywhere in any reasonable length you want to run; B) can be extended and SHARED with other components if you have limited jacks available. You just have to be careful to make sure only one digital source at a time is turned on while using the other; C) RCA cable is impervious to problems arising from tight bends; optical is too delicate and won't work well when bent. <<<<
My system is set up this way for one main reason: it allows casual TV, DVD/Blu-Ray watching (News, Weather, Imus in the Morning, etc) without the full-blown power-hungry audio equipment turned on at all.
When I want to melt the paint on my listening room walls I can also fire up the audio stacks and go ballistic with Top Gun on Blu-Ray, for example.
I never could understand the prevailing design goal of AV receivers and HTIB's to collect all video sources to a single point (of failure, possibly) and redistribute them to the TV or monitor. By design, that means you have to have the audio equipment turned on at all times to watch TV. Not very power-conservative and who needs hi-fi surround to watch Regis and Kathy Lee on live TV or Dave Chappelle on DVD?