Does a colder refrigerator keep things fresh longer?
Your refrigerator should be set so that it maintains a temperature no higher than forty degrees F.  This means that you shouldn't be opening the door frequently or leaving it open longer than necessary.  If you are aging beef in that refrigerator, you want the temperature to be no more than thirty-five degrees F according to some sources, but these sources conflict.  

Below 32 degrees F you are obviously duplicating the functionality of your freezer, but not as well.