Display Folder or file image based on a condition

Hi All
Am displaying the contents of a folder(folders n files) in a gridview.In the gridview,file/foldername ,type ,size ,Last modified date columns are displayed.the datasource for this gridview is supplied manually through a datatable.
I need to display folder/file images beside folder/filename.if the datasource is from a database we can give a if condition in the following way.
<ItemTemplate>
           <%# (If (Eval("type"))="folder" Then) %>
                    <asp:Image ID="folderimg.gif" runat="server" />
                    <%# else %>
                    <asp ...