the top and left menus are created dynamically. modifying this to work the way you want will require some hand editing.
the top menu is generated by the CSSMenuWriter/css_home/menu.php
the category links are created by this code:
<a href="<?php echo($assumedRoot); ?>Products_Results.php?Search=1&ProductCategoryID[]=<?php echo $row_menuwriter_categories["CategoryID"]; ?>"><?php echo $row_menuwriter_categories["CategoryName"]; ?></a>
if you named your results pages the same as the category name, substituting underscores for spaces, and made sure to use only alpha numeric characters, you could change this code to:
<a href="<?php echo($assumedRoot); ?><?php echo str_replace(" ", "_", $row_menuwriter_categories["CategoryName"]); ?>.php?Search=1&ProductCategoryID[]=<?php echo $row_menuwriter_categories["CategoryID"]; ?>"><?php echo $row_menuwriter_categories["CategoryName"]; ?></a>
for the left menu, you would need to edit the templates/main.dwt.php page.
edit the followong code:
$retHTML .= ' <div class="AccordionPanelTab" onclick="doHighlighlight(this);updateContant(\'Products_Results.php?Search=1&ProductCategoryID[]='.$row_SubCategoryList["CategoryID"].'\')">'.(($prevLevels>0)?substr($spaceStr,0,12*$prevLevels):'') .$row_SubCategoryList["CategoryName"].'</div>' . "\n";
to:
$retHTML .= ' <div class="AccordionPanelTab" onclick="doHighlighlight(this);updateContant(\''.str_replace(' ', '_', $row_SubCategoryList["CategoryName"]).'.php?Search=1&ProductCategoryID[]='.$row_SubCategoryList["CategoryID"].'\')">'.(($prevLevels>0)?substr($spaceStr,0,12*$prevLevels):'') .$row_SubCategoryList["CategoryName"].'</div>' . "\n";