Figures from technology researcher Gartner for the first quarter of 2013 show 246,000 fewer PC shipments than in Q1 2012. Some 4.99 million desktops and mobile PCs shipped in Australia in 2012.
Hewlett-Packard was the top vendor with 18.5 percent market share, followed by Apple (16.8pc), Dell (13.7pc), Lenovo (10.1pc) and Acer (10.0pc).
Acer shipments dropped 3 percent, which saw the Taiwanese maker fall from No 3 spot a year ago to fifth. Apple gained 2.6 percent to take second spot.
Analyst Lillian Tay said the figures show that tablet computer sales are cannibalising PC sales. Gartner is forecasting a more than 100 percent hike in Australian tablet sales from 2012 to 2014, with 6.94 million units set to be shipped.
She added that the sharp decline in both laptop and notebook shipments showed that Intel's drive to push up shipments through the advent of ultrabooks wasn't working.