Cerchi forse qualcosa del genere ?


<%@ Page Language="VB" %>
<%@ import Namespace="System.IO" %>
<%@ import Namespace="System.web" %>
<%@ import Namespace="Microsoft.Win32" %>

<script runat="server">


Public Sub WriteFile(ByVal Filename As String, ByVal AsAttachment as Boolean)
Dim Response As HttpResponse = HttpContext.Current.Response

Dim filepath As String = "/public/" & filename
Dim TheFile As FileInfo = New FileInfo(Filepath)
If (filepath Is Nothing) Then
Response.StatusCode = 404 'File Not Found
Response.End()
Exit Sub
End If


Response.ContentType = _
DirectCast(Registry.ClassesRoot.OpenSubKey(TheFile .Extension). _
GetValue("Content Type", "application\octet-stream"), String)
If (AsAttachment) Then
Response.AppendHeader("Content-Disposition", _
String.Format("Attachment; filename=""{0}""", filename))
End If
Response.WriteFile(filepath)
Response.End()

End Sub

</script>


poi richiamo la funzione passando le due variabili

writefile("nomedelfile",true)