You don't need to touch the old installation (i assume it came with RH9) Your new apache 2 would install, by default, in /usr/local/apache2. But to start it, you have to manually execute apachectl from /usr/local/apache2/bin, since the $PATH variable, which defines where to search for the command apachectl, points to the directory /usr/sbin, or something similar.
And if you want the new apache to be started at bootup, you need to edit a bootup script, /etc/rc.d/init.d/httpd
There are two definitions there:
you simply have to change that to the new installation, and it'll work. Have fun