opinions on CMSs (Drupal, Joomla, Mambo etc)

[Philip <subs%christiantena.net@localhost>]

I have been asked to sort out a new website because my church's website got 
hacked ( I think it was
running Mambo ).
I haven't really used a Content Management System before, but I have built a 
few Tomcat based
servers which is sort of getting close.
My main criteria is security, as I really can't cope with having security 
problems.  I guess that
the security of a CMS will depend largely on the quality of code.
Does anyone here have any strong opinions which CMS to go for, or to avoid?  
There are several
reviews around of CMSs but none of them say much about security.

thanks, Philip