[Dilettante_Pro]

Например, если минимум = 200px

<script type="text/javascript">
function setHeiHeight() {
   $('.one_screen').css({
        height: ($(window).height() > 200 ? $(window).height() : 200)  + 'px'
     });
}
setHeiHeight();
$(window).resize( setHeiHeight );
</script>