In most cases, if you can run component connections, then do so. But realize that it may or may not give a better picture than S-video. Depends on the quality/size of your tv, the quality of the cable purchased, etc. etc. If possible, buy both types and try them and decide for yourself. Then return the other.
And if you don't know this already, proper calibration (video and audio) will most likely have a huge effect on your viewing & listening pleasure.
To answer your question you can just run the components straight to the TV, or you can route them through the receiver and have your receiver switch. Although there wouldn't be much of a need for this unless something besides your dvd player uses components out. Andy
How you connect your video is kinda up to you, as Chris stated patching the video through the receiver leaves more room for degradation and interference, but you also get the convenience of your audio automatically switching to whatever your viewing, rather than changing the input on the tv and on the receiver. The amount of signal loss may not even be noticable. I suggest you try patching it through the receiver and a direct connection and see for yourself if you can tell and go from there. As far as audio goes I suggest runing everything into it. wouldn't make much sense to have a dvd player and run it through your TV when you have a nice HT setup sitting there Andy
Let me just restate that if you do not have more than one source with component video output, there is no need to go through the receiver at all, as that will simply mean you need one more cable and you are gaining little or nothing but a few less buttons to push.