something along the lines of
Code:
{if $cat eq "1"}
Show this header HTML
{else if $cat eq "2"}
Show that header HTML
{/if}
{/if}
etc.
You can detect if the customer is on the homepage
http://forum.x-cart.com/viewtopic.php?t=12667
or if they're in a particular static page
Lots of handy tips here
http://forum.x-cart.com/viewtopic.php?t=12234
HTH