Zaskrtnuti checkboxu

<div id="seznam-pc">
<?php
    for ($i=1; $i<=$pocetPC; $i++) {
        echo '<label>PC '.$i.'<input type="checkbox" name="pc-'.$i.'-check" /> </label> <br />';
        echo "\n";
    };
?>
</div>

<fieldset>
    <form name="pc-form" method="post" action="/martin/web.php?akce=&zpracovano=ano"> 
<div id="ovladat-vsechny-pc">
        <label>Všechny
            <input type="checkbox" name="pc-vsechny" />
        </label>
</div>

 <div id="seznam-pc">
<label>PC 1<input type="checkbox" name="pc-1-check" /> </label> <br />
<label>PC 2<input type="checkbox" name="pc-2-check" /> </label> <br />
<label>PC 3<input type="checkbox" name="pc-3-check" /> </label> <br />
<label>PC 4<input type="checkbox" name="pc-4-check" /> </label> <br />
<label>PC 5<input type="checkbox" name="pc-5-check" /> </label> <br />
</div>        
        <input type="submit" value="Odeslat" />
    </form> 
</fieldset>