You can turn off the netstd ftpd by commenting out the apprpriate line in /etc/inetd.conf and then '/etc/init.d/netbase restart'.
As for proftpd, I am not sure if it wants to ru under inetd or as its own daemon. Look for an entry (maybe commented out) in /etc/inetd.conf, look for /etc/init.d/proftpd, and try th eproftpd manpage to see how proftpd wants to be started. If it needs inetd but doesn't ahve a line in there, copy the line from the original ftpd, but substitue the path to proftpd instead of in.ftpd Carl