This method that you are proposing will really only deal with the script kiddies and won't deal with those with a lot more finesse. A better course of action would be to secure the server, have a firewall in front of the web server and an IDS behind it to detect any intrusions.
I agree 100%, as this not only being a faster method but a much more secure one. I've also noticed that the McAfee virus scanner when running in the background constant mode detects a majority of script kiddie applications based upon the hashes(terminology correct?) that makes up the file, rather than the name. Port scanners, crackers, etc etc... I've seen that virus scanner pick up the most amazing things, and in the process save quite a few networks while firing a few employees.