I tried to get them to replace the screen on a laptop a while back and was informed that it took a minimum of 5 (I think?) pixels before Dell would replace it. On those Dell rebadged LCD's I would guess at least 5 would have to be bad before they would consider replacing it. On any other non-Dell LCD that you bought from Dell, you'd have to take it up with the manufacturer. Dell will just laugh at you if it doesn't have their name stamped on the product and then tell you to go talk to the manufacturer about RMA'ing it.
techfuzz