If your TV can handle a 1080i input (which it almost certainly can), then it will line double and display 1080p. Your TV will convert all input signals that it can handle to 1080p.
You might also want to experiment with the other output settings on your DVD player, as it may be that the TV can upconvert the 480i signal better than the DVD player can. Or you might find it best to send a 480p signal or a 720p signal to the TV. What will be best all depends on how good your DVD player is at each type of conversion, and how good your TV is on each type of conversion. Try all possibilities and use whatever setting looks best to you.
