Ok, this will work, and before you ask to have it altered for each button on your form, why not give it a go on your own first

VB Code:
  1. Private Sub btnUntil_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnUntil.Click
  2.         Dim sbMessage As New System.Text.StringBuilder
  3.         Dim Indx As Int32 = 0
  4.         If Me.lstParts.SelectedItems.Count > 0 Then
  5.             sbMessage.Append("This is a Do Until loop and you chose the following items: ")
  6.             Do Until Indx > Me.lstParts.SelectedIndices.Count - 1
  7.                 If Indx = 0 Then
  8.                     sbMessage.Append(Me.lstParts.SelectedItems(Indx).Text)
  9.                 ElseIf Indx = Me.lstParts.SelectedIndices.Count - 1 Then
  10.                     sbMessage.Append(" and ").Append(Me.lstParts.SelectedItems(Indx).Text)
  11.                 Else
  12.                     sbMessage.Append(", ").Append(Me.lstParts.SelectedItems(Indx).Text)
  13.                 End If
  14.                 Indx += 1
  15.             Loop
  16.             txtLoop.Text = (sbMessage.ToString)
  17.         Else
  18.             MessageBox.Show("You did not select any items", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
  19.             Exit Sub
  20.         End If
  21.     End Sub