If the div elements are 100% of the height of the window , then your HTML + CSS markup comes down to:
<div id="left">Liquid layout</div>
<div id="right">Fixed width 450px</div>
html { height: 100%; }
body { height: 100%; margin: 0; padding: 0; }
#left { position: absolute; top: 0; bottom: 0; left: 0; right: 450px; }
#right { position: absolute; top: 0; bottom: 0; right: 0; width: 450px; }
Demo here
div , " " : (i) (ii) float (iii) (iv) div
<div id="parent">
<div id="left">Liquid layout</div>
<div id="right">Fixed width 450px</div>
<div class="clear"></div>
</div>
#parent { border-right: 450px solid orange ; background-color: yellow ; }
#left { float: left; width: 100%; }
#right { float: right; width: 450px; margin-right: -450px; }
.clear { clear: both; }