show files from folder help.

Hi.

I have a script that shows some files from a folder.
code_behind

Code:

---

Sub fileinfo()
        Dim objDI As New System.IO.DirectoryInfo(Server.MapPath("upload/files/"))
        Dim allFile As New ArrayList()
        allFile.AddRange(objDI.GetFiles("*.png"))
        allFile.AddRange(objDI.GetFiles("*.jpg"))
        allFile.AddRange(objDI.GetFiles("*.bmp"))
        allFile.AddRange(objDI.GetFiles("*.gif"))
        allFile.AddRange(objDI.GetFiles("*.pdf"))
        allFile.AddRange(objDI.GetFiles("*.doc"))
        allFile.AddRange(objDI.GetFiles("*.docx"))

        Me.showfiles.DataSource = allFile
        Me.showfiles.DataBind()
    End Sub

---

main_code

Code:

---

<ul class="thumbnails">
      <asp:DataList ID="showfiles" runat="server" RepeatColumns="6" CellPadding="10" RepeatLayout="flow">
            <ItemTemplate>
                  <li class="span2"><a class="thumbnail" href="#"><asp:ImageButton ID="folderfiles" runat="server" ImageUrl='<%# string.Format("upload/files/{0}", DataBinder.Eval(Container.DataItem,"Name")) %>' ToolTip='<%# Bind("Name") %>' height="82" width="119" /></a></li>
            </ItemTemplate>
      </asp:DataList>
</ul>

---

works fine with images, but if i add a document like a pdf file i get this.
Attachment 90865

then it add the textbox, how can i add an if statsment or something that can add:
pdficon.jpg for .pdf files
docicon.jpg for .doc files
zipicon.jpg for .zip files

so if the file is an image then it works like now, and when the file is an pdf or doc file, then it use the icon image and display that !?