Date/Time Stamped and Numbered filenames when saving to jpeg?

[mench2]

Right now the existing VB code I have uses GUID to generate "random" filenames on save.

For instance:

ff8514d389a041649fd8b925a32f2b51.jpg
e1c938560fc1464ab2138065fc4661d3.jpg

Instead I want a date stamp and numbered filename:

for instance:

20091015_131644_001.jpg <--(Date_Time_NumberIncrement)
20091015_131551_002.jpg

Or something along those lines...

The current code (which saves a jpeg to a random GUID filename) is below:

Imports System.Web
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.IO

' To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
' <System.Web.Script.Services.ScriptService()> _
<WebService(Namespace:="http://tempuri.org/")> _
<WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Public Class Service
     Inherits System.Web.Services.WebService


    <WebMethod()> _
    Public Function SaveJPEG(ByVal strJPEG As String) As String

        'saves an uploaded photo and returns a unique name reference

        Dim BinaryContent As Byte() = Convert.FromBase64String(strJPEG)

        Try
            'generate a unique name (GUID) for the filename
            Dim strFileName As String = System.Guid.NewGuid.ToString("n")
            '
            
            Dim fStream As New FileStream("D:\photos\" + strFileName + ".jpg", FileMode.CreateNew)

            Dim bw As New BinaryWriter(fStream)

            bw.Write(BinaryContent)
            bw.Close()
            fStream.Close()

            'return the filename for use in Flash
            Return strFileName

        Catch ex As Exception

            Return ex.Message

        End Try

    End Function

End Class