CIao bello!
Io farei cosi', cioè faccio cosi':

Mi creo una classe personalizzata (Name, Surname) ...

codice:
        Dim DS As New DataSet
        Dim DT As New DataTable
        Dim ArrNormal As New ArrayList
        Dim ArrAdmin As New ArrayList
        Dim xmlFileName As String = "../File/user.xml"
        Dim fsReadXml As New System.IO.FileStream _
               (xmlFileName, System.IO.FileMode.Open)
        DS.ReadXml(fsReadXml)
        For Each row As DataRow In DS.Tables(0).Rows
            If CType(row("type"), String) = "Normal" Then
                ArrNormal.Add(New MyUser(row("name").ToString, row("type").ToString))
            Else
                ArrAdmin.Add(New MyUser(row("name").ToString, row("type").ToString))
            End If
        Next
A questo punto la mia ArrayList mi fa da DataSource ...

ComboBox1.DataSource = ArrNormal
ComboBox1.DisplayMamber = "Name" --> Proprietà della classe