Private Sub TextBox1_TextChanged(ByVal sender As System.Object, _
  ByVal e As System.EventArgs) Handles TextBox1.TextChanged
 
  Select Case TextBox1.Text
    Case "1"
      TextBox1.BackColor = Color.Red
    Case "1,5", "1.5"
      TextBox1.BackColor = Color.Orange
    Case "2"
      TextBox1.BackColor = Color.Green
    Case Else
      TextBox1.BackColor = Color.FromKnownColor(KnownColor.Window)
  End Select
End Sub

_________________________
Professionelle Entwicklerkomponenten
www.tools4vb.de