The Apache’s ServerTokens directive controls whether Server response header field which is sent back to clients, includes a description of the generic OS-type of the server as well as information about compiled-in modules.
As many worms/viruses check the Server header before attempting an exploit in order to choose the best attack available, it could be a good idea to provide the minimal information possible (the default is to provide full information). Edit your httpd.conf and add the following:
ServerTokens Prod
This will only send the string Apache in the Server header.
Note that this would not stop skilled bad guys, but would slow down those kiddies playing around.