Dice and boil potatoes(with skin on) and eggs about 20 minutes in a pot together.  Boil macaroni separate for 15 minutes.  Let all the hot items cool for 30 minutes.  Mash eggs up not too coarsely but not too small either. Mix the mayo and dijon mustard into the cooled down ingredients using a folding motion as not to smash up the potatoes.  Chill for at least 3-4 hours but overnight would be best.

With the mayonnaise I say 1.5 cups but of course it is at your discretion if you want the salad to be more or less moist so you can either use more mayo or lighten up on it.