Netscape 6: Changing "new mail" notification

[Piper the Worm]

Hey, just wondering if anyone knew how to change the sound it plays when 
you have new mail.... and, if there's an option to have the little mail 
thing go into the taskbar when you have new mail like it did in 4.78. 
It seems to play the default sound, but I want it to point to something 
else... Couldn't find it in my control panel/sounds.  Thanks.