Is a RPM available for Centos5 yet ?
Enable the RPMForge repository to get the latest SA. I just did a check-update and it's got 3.2.4 available.
RPMForge also carries a number of related packages, such as MIMEDefang and ClamAV.
Here's how to add the repository to your yum configuration: <http://wiki.centos.org/Repositories/RPMForge>