you would need to see the screen for GPS, MP3, things like that. You should NOT be watching a DVD while driving down the street!
What I meant was, You have to look at the screen at some point. I look at the screen while im driving all the time. I dont stare at it though. I guess glance is a better term. If you're scrolling through your mp3's and trying to find a song, its normal to look at your screen. I'm sure im not the only one that does it. My screen is mounted just below my headunit so my eyes arent off the road for more then a few seconds.
Also for GPS you may need top glance to see where the next turn is etc. And if ur at a stop sign it won't hurt. You probably wont be able to see road names if it were in the glove box unless ur screen is pretty big and the font is big and bold.