Dude, the Primus that filed for bankruptcy is in Delaware. Delaware is not in Australia. The Primus in Aussie is the one at www.primus.com.au

Where I work (local government, 250 user site, Parramatta, NSW in Australia) we had the same request for an ITIL-compliant helpdesk system. We chose RT because it was a) free b) fit into our system c) we could buy the O'Reilly book and d) there was a support community for it.