As for squid I'd go with the latest 2.6, it's very stable
despite the fact that it's still a development version, and
for the dansGuardian: http://www.harvest.com.br/asp/afn/wcfp.nsf/449683f58d33d9bb83256e3e007f50a6/6e7a75df8c1f81b203257130000629ad/$FILE/dansguardian-antivirus-6.4.4-1.src.rpm
It's a patched DG with AntiVirus support.
(Hope the link isn't based on my PHP session :} ... if it is,
start looking here: http://www.harvest.com.br/asp/afn/dg.nsf