ONMOUSEOVER="status='Hola Palomita'; return true"
This codes states put 'Hola Palomita' in your browsers status bar.

ONMOUSEOUT="status=''; return true"
This code clears your browsers status bar when the mouse is released. 
Caution: The quotes after the Status bar are two single (') quotes not one double (").

  IMG src="TestButton.gif" alt="Hola Palomita" border=0 
   
This identifies the graphic that will cause this change when moused over. 
Attn: Text can be used in place of a graphic when using this code!!!

alt="Text In Status Bar"
A good habit and another way the user can have an alternate name for this button or graphic.