Help needed for javascript saveas dialog box

Hi,

      I am using asp.net , C#, FrameWork 3.5. Fileupload control i am using link button. If the user click the filename below command open the file.  Instead of open i want to enable the saveas dialog box. 
string popupScript = "<script language='javascript'>window.open('" + localFilePath.Replace("~", "..") + "', 'saveas', 'width=925px,height=450px,left=165,top=200');</script>";
ScriptManager.RegisterStartupScript(this Go to the complete details ...