You may have heard that all Xbox 360 DVD drives manufacturered after November '06 were getting the quieter BenQ drives. Why's this important? Because the earlier models were like having your wife blow-dry her hair every time you were trying to play Gears online.
So how do you tell which one you've got? Xbox Scene has a comparison with all three drives. Toshiba/Samsung on the left, Hitachi/LG in the middle, and BenQ on the right. If you've just purchased a drive in the last few weeks and don't have the BenQ drive, take it back to the store for an exchange and see if you can get lucky.