The common practice for centering form labels and inputs involves using 2 columns, with labels being right-aligned and input fields left-aligned.
To achieve this layout without relying on tables, one approach is to assign equal widths to label elements and right-align them, as demonstrated below:
<style type="text/css">
.foolabel{width:10em;text-align:right;display:inline-block;margin-right:1em;}
.formlist{list-style:none}
</style>
<ul class="formlist">
<li><label class="foolabel">Name:</label><input type="text" /></li>
<li><label class="foolabel">Quest:</label><input type="text" /></li>
<li><label class="foolabel">Favorite Color:</label><input type="text" /></li>
</ul>