Apple took 15% of the market, ahead of both Acer (14%) and Dell (13%) for the first time. Toshiba was in fifth place with 9%.
HP stayed in top spot with 22% of the ANZ market.
"While most vendors' performance slowed in Q3, HP, in particular, took the strongest hit. There were delays in government project roll outs while HP's channels cut back in stock intake as a precautionary measure in view of market softness," said IDC market analyst, Amy Cheah. "The unfortunate 'PSG spin off' debacle also momentarily affected confidence in HP's strategic outlook which opened a window of opportunity for competitors such as Apple to gain share."
Apple shipments up - see page 2.
Unlike most other vendors, Apple managed to increase its unit shipments during the quarter, Ms Cheah told iTWire.
An Apple spokesperson declined to comment on IDCs figures.
IDC is predicting 1.77 million PCs will be shipped during the current quarter, and that the hard disk shortage caused by the floods in Thailand will not bite until 1Q12. Perhaps optimistically, the firm predicts a recovery from that situation in 2Q12.
"Though this issue impacts the supply-side more than demand, the effect of tightening HDD supply will cascade down to end users as vendors limit promotions and shift focus to premium products to balance out profit margins. Consumers who are generally more price sensitive will feel more of the pinch when the higher cost of HDD is passed on to end users," said Ms Cheah.