Thanks for the help. I located the file you specified, made the changes, and nothing. I even deleted the file altogether (local test machine), nothing happens.
It is the only file by that name on my system.

The section creating the box is in my
includes/templates/templates_default/templates/tpl_advanced_search_default.php .

In my file it is line 28 which is:

<div class="centeredContent"><?php echo zen_draw_input_field('keyword', $sData['keyword'], 'onfocus="RemoveFormatString(this, \'' . KEYWORD_FORMAT_STRING . '\')"'); ?>&nbsp;&nbsp;&nbsp;<?php echo zen_draw_checkbox_field('search_in_description', '1', $sData['search_in_description'], 'id="search-in-description"'); ?><label class="checkboxLabel" for="search-in-description"><?php echo TEXT_SEARCH_IN_DESCRIPTION; ?></label></div>

The zen_draw_input_field is what I need to alter in order to specify the input size, but I can't find and am not sure how to modify the function this relates to.