i just upgrade to a hp dvd420i cd drive, and i what to ask a question
you should be able to play DVD video use the hp dvd player, but i have a problem i try 2 differnt player like window media 9 for one but i have no sound, but yet if i put a audio music cd in dvd drive i get sound, it ther something i can to fix this

DF
Can you see the dvd when played? (watch the film)

To be able to play DVD's you have to install DVD software. Something like WinDVD or PowerDVD. Do you have this type of software installed?

Heere is a link with the relevant software list. I do not know if there are any free pacakeges in there.
http://www.digital-digest.com/dvd/downloads/showallsoftware.php

Was this DVD drive a retail purchase or OEM??

Usually with retail, a "player" as Ernie pointed out is necessary to view DVDs, and the software to do so is bundled with the purchase...

If you have Video then you missing Audio codecs---I was having a problem with Audio until I installed "ac3filter" its a 434KB .exe file that really brings Windows Media Player and DivX Player up to speed.Go to Google and search out this file.Either way install this free patch.