15
Try this...
comboBox1.DataSource = Enum.GetValues(typeof(MyEnum))
.Cast<MyEnum>()
.Select(e => new { Value = e, Description = e.ToString().Replace("_"," ") })
.ToList();
comboBox1.DisplayMember = "Description";
comboBox1.ValueMember = "Value";
...although, I would be more inclined to use a "Description" attribute (as per Steve Crane's answer).