Salve MItaly, chiedo scusa ma ancora non so muovermi bene.
Ho provato a seguire la guida compilando in questo modo ma non mi pensa proprio:

'' Create a new 'Uri' object with the mentioned string.
Dim aggexe As New Uri("http://mio_sito/FILE.exe")
'' Create a new 'HttpWebRequest' object with the above 'Uri' object.
Dim myHttpWebRequest As Net.HttpWebRequest = CType(Net.WebRequest.Create(aggexe), Net.HttpWebRequest)
'' Create a new 'DateTime' object.
'Dim targetDate As DateTime = DateTime.Now
'targetDate.AddDays(-7.0)
'myHttpWebRequest.IfModifiedSince = targetDate
Dim dataaggsoft As DateTime = #1/10/2014#
myHttpWebRequest.IfModifiedSince = dataaggsoft
Try
' Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
Console.WriteLine("Response headers for recently modified page" + ControlChars.Cr + "{0}" + ControlChars.Cr, myHttpWebResponse.Headers)
Dim streamResponse As Stream = myHttpWebResponse.GetResponseStream()
Dim streamRead As New StreamReader(streamResponse)
Dim readBuff(256) As [Char]
Dim count As Integer = streamRead.Read(readBuff, 0, 256)
Console.WriteLine(ControlChars.Cr + ControlChars.Cr)
While count > 0
Dim outputData As New [String](readBuff, 0, count)
Console.Write(outputData)
count = streamRead.Read(readBuff, 0, 256)
End While
' Close the Stream object.
streamResponse.Close()
streamRead.Close()
' Release the HttpWebResponse Resource.
myHttpWebResponse.Close()
Console.WriteLine(ControlChars.Cr)
Console.Read()
Catch f As WebException
If f.Response IsNot Nothing Then
If CType(f.Response, HttpWebResponse).StatusCode = HttpStatusCode.NotModified Then
Console.WriteLine((ControlChars.Cr + "File troppo vecchio" + dataaggsoft))
Else
Console.WriteLine(ControlChars.Cr + CType(f.Response, HttpWebResponse).StatusCode)
End If
Else
Console.WriteLine(ControlChars.Cr + f.Message)
End If
End Try


Molto probabilmente non riesco a compilarlo bene. chiedo scusa ancora ma è la prima volta che mi imbatto nelle proprietà HttpWebRequest.IfModifiedSince, ho sempre usato ftp (senza pensare alle date ovviamente).
Se mi potete dare una mano???
Grazie infinite