In order to change the layout, you have to edit the following stylesheets:
xslt/front//live/main.xsl
xslt/root.xsl
There are currently two layouts:
xslt/page_lenya.xsl
xslt/front//body_lenya.xsl
and
xslt/page_q42.xsl
xslt/front//body_q42.xsl
At the moment you have to edit the following XSLT in order to modify the global navigation on the left hand side:
xslt/page_lenya.xsl
Of course the navigation would actually belong into a common XML, but who is going to change that?!