procedure FileCopy(const SourceFileName, TargetFileName: string );
var
S, T: TFileStream;
begin
S := TFileStream.Create(sourcefilename, fmOpenRead );
try
    T := TFileStream.Create(targetfilename, fmOpenWrite or fmCreate);
   try
     T.CopyFrom(S, S.Size ) ;
   finally
     T.Free;
   end;
finally
   S.Free;
end;
end;