NSW RTA chief information officer, Greg Carvouni told ZDNet Australia while system outages or slowdowns resulting from attacks would "inconvenience" someone working in an office environment, they were "fatal" for someone working in a customer service role in a registry.
Carvouni said a virus had created a day of disruption within the RTA several months ago -- a level which, translated to loss of a day's production at registries, was "not acceptable".
Sun Microsystems announced last week it would migrate 1,500 of the NSW RTA's users -- based in 120 offices -- from Microsoft Exchange to Sun's Java System Messaging and Calendar Servers for e-mail and calendaring.
Carvouni said other key reasons for the move were lower total cost of ownership of the Sun solutions and the benefits derived from a centralised platform combined with a thin-client architecture.
He noted reductions in telecommunications costs meant the RTA could purchase more bandwidth while bringing servers back from sometimes remote locations to centralised data centres.
He said despite the decision to go with Sun, the RTA was maintaining a good relationship with Microsoft, who was "aware of its concerns".
The RTA still has 5,500 employees using Microsoft desktop environments.