Not saying it wouldnt be okay, just un-nessasary, because, as i've stated mirc beeps, the only way it wont beep is if you turn mirc beeps off, because even if you dont have external speakers, mirc can be set to use your internal ones.
Also i pretty "obvious" (although the same happens to be, I will admit), visual sign is the position of your scrollbar.
Eamonn.