Best way of blocking anyone roaming your directories is to alter a line in your httpd.conf file. You need to open up httpd.conf and look for the line that reads
<Directory "/usr/local/apache/htdocs">
then scroll down the file until you find a line that starts
Options
it will probably have the word Indexes on the line you need to make it read
Options -Indexes FollowSymLinks MultiViews
This will block the server generated directory views. now if anyone trys to get into your directories at will not show anything that you dont want them to see.
Oh on a more basic note you can block the directory view by putting an index.html file in each subdirectory this is the file that any file server looks for before displaying the directory list.
Mark.