Encontre hace un tiempo esta funcion en CSharp y la converti a VB
Código:
Public Function ToMd5(ByVal sPass As String) As String
Dim md5 As MD5 = New MD5CryptoServiceProvider
Dim dataMd5() As Byte = md5.ComputeHash(Encoding.Default.GetBytes(sPass))
Dim sbEnc As StringBuilder = New StringBuilder()
Dim i As Integer
For i = 0 To dataMd5.Length - 1
sbEnc.AppendFormat("{0:x2}", dataMd5(i))
Next
Return sbEnc.ToString
End Function