hier ist die lösung
var farben=new Array("#f0f0f0","#f0f0f0","#f0f0f0");
function an(nr){
if(document.getElementById){
for(i=0;i<farben.length;i++){
if((nr-1)!=i){
document.getElementById("C"+(i+1)).style.backgroundColor="#FFD700";
};
};
};
};
function standard(){
if(document.getElementById){
for(i=0;i<farben.length;i++){
document.getElementById("C"+(i+1)).style.backgroundColor="#f0f0f0";
};
};
};
</script>
</head>
<body>
<table border="1" cellspacing="0">
<tr>
<td id="C1">ja<input type="radio" name="status" value="0" onclick="an('2')"></td>
<td id="C2">nein<input type="radio" name="status" value="1" onclick="standard()"></td>
</tr>
<tr>
<td id="C3" colspan="2">Farbe</td>
</tr>
</table>