[JRD!]

Add this function in your script, i made the choice to define megabytes...

Function MbOrTb(Byte: Extended): String;
begin
if Byte < 1024 then Result:= NumToStr(Byte) + ' MB' else
  if Byte/1024 < 1024 then Result:= NumToStr(round(Byte/1024*100)/100) + ' GB' else
     Result:= NumToStr(round((Byte/(1024*1024))*100)/100) + ' TB'
end;