[spasibo]

<script type="text/javascript">
function isright(obj)
{if (obj.value>1000) obj.value=1000;  
if (obj.value<20) obj.value=20;}
</script>
<script type="text/javascript">
function da(obj)
{if (obj.value>100) obj.value=100;  
if (obj.value<0) obj.value=0;
}</script>


<input type="text" size=16 class="num_only" value(hidden)="1000" onkeyup="this.value=this.value.replace(/[^0-9]+/g,''); isright(this);">
<input type="text" size=16 class="num_only" value(hidden)="100" onkeyup="this.value=this.value.replace(/[^0-9]+/g,''); da(this);">