Some people may check your server by trying to find 404 not founds in which your apache version is displayed. Here is how you turn it off.
pico -w /etc/httpd/conf/httpd.conf (or wherever your httpd.conf is located)
ctrl - w and put in 'ServerSignature'
change
Code:
ServerSignature On
to
Code:
ServerSignature Off
service httpd restart
and your Apache 1.3.31 is now gone.
Cheers.