Code Snippet for random key generation in C#

Code Snippet for random key generation in C#:

private string generateSerialNum()
{
     Random r = new Random();
     StringBuilder sb = new StringBuilder();
     int size = 14;
     string legalnums = "0123456789";
   for (int i=0; i<9;i++)
   {
        sb.Append(legalnums.Substring(r.Next(0,legalnums.Length-1)+1,1));
} return sb.ToString();
}

private void SaleOrder_Load(object sender, EventArgs e)
{
    txt_SalesID.Text = generateSerialNum();
}


Cheers,
Venkatesan Prabu .J