function switchBackground( radio ) 
{
	// label associated with the radio button
	label = document.getElementById("label_"+radio.id);

	// uncheck all the other radio buttons
	inputs = document.getElementsByTagName( "input" )
	var input = null;

	for ( var i=0; input = inputs[i]; i++ )
	{
		if ( input.type == "radio" && input.name == radio.name )
		{
			document.getElementById("label_"+input.id).className = "";
		}
	}

	// check this one
	label.className = "checked";
}