Hi,
How to secure a wordpress web site? My friends website is hijacked and all the post titiles were changed as hijacked by so and so.
Here is a good resource on securing WordPress:
http://codex.wordpress.org/Hardening_WordPress
Wordpress is rather hard to hack now adays. If your friend is backing up his site and updating the CMS to the most recent version, the only other problem that I can see is that they are not managing their access to their blog well or use an easy password. It sounds more like a problem with the user being hacked on their computer rather than someone only hacking their wordpress.