The global PC industry underwent a major realignment in the third quarter of this year with Taiwanese computer brand Acer surging past American computer maker Dell to take second place behind overall leader HP.

According to the latest survey by research firm IDC, the back-to-school season drove the demand for Acer’s low-cost netbooks, with the vendor outperforming the market in virtually all regions.

HP, on the other hand, exploited its advantage in retail and expansion in telco bundle offerings to grow 9.3 percent from last year. The vendor performed above market in most regions, with the company regaining the top spot in the US, said IDC.

Dell, meanwhile, experienced a worldwide decline year over year. It, however, saw solid growth in emerging markets, especially in Asia Pacific excluding Japan.

Global PC shipments rose 2.3 percent year on year in the third quarter of 2009, an improvement from the declines of 6.8 percent in the first quarter and 2.4 percent in the second quarter of this year.

“Seeing market growth ahead of the launch of Microsoft’s Windows 7 bodes very well for the fourth quarter and next year, IDC said. “All regions except Japan either met or surpassed expectations. Portable PCs continue to account for the majority of volume and growth.”

The research firm noted that despite the ongoing mix of gloom and caution on the economic front, the PC market continues to rebound quickly.

“The competitive landscape, the transition to portables, new and low-power designs, growth in retail and consumer segments, and the impact of falling prices are all reflected in the gains by HP and Acer, as well as overall market growth,” it said.