If you have a good antenna already, I would just stick with that. Some people have it work great, others need to go out and buy an "HDTV" specific antenna. I would try the one you have for the time being. I think it will work.
Originally Posted by Walmart
HDMI, component video, S-video, audio and computer connections
For your computer I would use "computer connections". That's likely VGA or DVI, but it doesn't specify. You might have to buy a cable if one is not included. (I don't think they will include it) You need to find out whether its VGA or DVI first, though.
For your DVD player, I would use the HDMI, Component, or S-Video input (in that order). The DVD manufacturer probably included one of these cables with your player. If they just gave you Composite (old school RCA), you might need an S-Video converter or just purchase a new compatible cable.
Let us know if you need any other information.