You may also want to be sure that all your settings on both the TV and the DVD are correct.
An LCD/TV allows for video and computer connections, so sure you should be able to connect your computer and use it to play DVD's. For most people, having the computer in the same room as your main entertainment TV was not done. Now we have media centers working their way into our home theatres. As for just connecting a regular PC, that may be fine, but how do you plan on controlling the DVD player?
Most of us are used to having a remote in our hands, we turn the TV on, and there is a picture, we put a disc in, switch inputs and there is a picture, all this being done via remote control, or a universal remote.
I just bought a 40" LC TV with 1366x768 resolution. The DVD player I have was connected to my 29" CRT using the component cables (Red, Blue and Green) but using that same connection on the new LCD doesnt give THAT great of a picture. This is prolly coz my DVD player's output is 480 instead of 720.
Now, instead of buying a new DVD player, can I connect my PC with DVI/DSUB connection and use that to play DVDs using PowerDVD or some other application? Would that result in a better output? If yes, why dont most people use this instead of gettting a dedicated HD DVD player?