Acer's Gateway acquisition positioned it as the world's third-largest PC vendor two years ago. Now, boosted by a 16.6% year-over-year growth in notebook shipments, the company has officially leapfrogged past Dell to take the second spot just behind HP. According to the latest figures from iSuppli, the Taiwanese firm commanded 13.4% of global shipments in Q3 2009, compared to 19.9% for HP and 12.9% for Dell.

Lenovo was the only other company in the top five to see similar growth and actually jumped by a higher 17.2 percent, but remained in fourth place with 6.94 million units shipped. Meanwhile, Dell actually dropped 5.9 percent to ship 10.34 million PCs versus the 10.99 million last year. Rounding out the top five sellers was Toshiba, which grew 9.7 percent from the same period last year with 4.01 million units shipped.

Overall global shipments reached a total of 79.9 million, up 1.1 percent from the 79.1 million units shipped in Q3 2008. That growth was strong enough for iSuppli to revise its forecast for the whole year. Rather than falling by 4% as it previously expected, the company now says 2009 shipments to go down by 0.9% compared to 2008.