1Scrub potatoes. Leaves skins on if desired, or peel thinly and remove eyes.
2Heat 1 inch water (salted if desired) to boiling; add potatoes. Cover and heat to boiling; reduce heat. Cook 30 to 35 minutes or until potatoes are tender; drain. Cool slightly; cut into cubes (about 6 cups).
3Mix mayonnaise, vinegar, mustard, salt and pepper in 4-quart glass or plastic bowl. Add potatoes, celery and onion; toss. Stir in eggs. Cover and refrigerate at least 4 hours.