Visual Basic

Imports System
Imports System.Management

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        TextBox1.Text = GetHddSerial()
    End Sub

    Public Function GetHddSerial() As String
        Dim query As New SelectQuery("Win32_PhysicalMedia")
        Dim search As New ManagementObjectSearcher(query)
        Dim info As ManagementObject
        Dim strSerial As String = ""
        Dim i As Integer
        For Each info In search.Get
            strSerial &= info("SerialNumber").ToString
            i += 1
            If i = 1 Then Exit For
        Next
        Return Trim(strSerial)
    End Function
End Class

Private Sub TextBox2_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox2.KeyPress

        If Keys.Enter Then
            SendKeys.Send("{TAB}")
            Exit Sub
        End If

        Select Case e.KeyChar
            Case "0" To "9"
            Case Microsoft.VisualBasic.ChrW(8) 'backspace
                'Case Microsoft.VisualBasic.ChrW(46) 'dot (.)
                '    If InStr(TextBox2.Text, ".") > 0 Then
                '        e.Handled = True
                '    End If

            Case Else
                e.Handled = True
        End Select

    End Sub