This can be a confusing topic because there are so many opinions as to "when the bird is done."  Sources can range from grandma ("When the leg moves and the juices run clear"), to antique cookbooks which generally advise cooking all poultry and pork until it resembles shoe leather, to modern cooking sources where the recommended temperature can swing up to 15 degrees depending on which one you reference.  Even reputable cooking magazines can offer up poultry recipes that seem to contradict each other.

The difference between the recipes is likely due to the method of roasting. If the bird is roasted at a low temperature (200 degrees), the dark meat can reach 175 to 180 degrees and not be overdone, as the meat is evenly and slowly cooked. If, however, the chicken is roasted in a 450 degree oven, the outer portion of the breast will be overdone and dry while the dark meat temperature is a mere 160 degrees

The bottom line is that you have to have enough heat to kill the baddies (which tend to die at around 140 degrees or so), but not so much that the meat dries out.  This is compounded by the fact that white meat dries out faster than the fattier dark meats, so that even on the same bird the doneness criteria is not the same.

The ranges given below should ensure that you get tender, moist meat that is free of any harmful bacteria.  Within these ranges it becomes a matter of your personal preference - a little experience will guide you to the perfect doneness criteria for you.