Thanks, all! I'm going to give these suggestions a try.
I'm new to ASP and shopping carts/VP-ASP, but I managed a temporary work-around that displays a blurb of text on the top-level shopdisplaycategories.asp page. I'm just not sure it's a terribly clean way to do things.
I added a "<!--#include file="frontpagetext.asp"-->" statement to shoppage_header.htm, then in frontpagetext.asp, put this:
<%
if Session("currenturl")="shopdisplaycategories.asp" then
if highercategoryid="0" then
response.write "Front page text"
end if
end if
%>
It seems to display my front page text only on the top level, without breaking subcategory pages. But again, it doesn't seem very clean to me!