Consumer portables, particularly netbooks, were the only area of growth that salvaged the lackluster worldwide PC market, a new report from IDC showed.

The global PC segment fell 2.4 percent year-on-year in the second quarter of 2009, while shipment value was down 19.1 percent over the same period, according to IDC’s Worldwide Quarterly PC Tracker.

Shipments of consumer portables increased by 44 percent from a year ago – rebounding from a low of 28-percent growth and approaching the 44-55 percent range of 2007 and 2008.

However, the analyst firm noted that commercial portables growth remained depressed at – 16 percent, and desktop volumes declined 17 percent as businesses limited spending and the market continued its shift to portable PCs.

Within consumer portables, traditional notebooks recovered to 13 percent year-on-year growth from almost no growth in the first quarter, but shipment value was down 6 percent.

The share of netbooks, which IDC dubbed “mini-notebook,” in consumer portables was up to almost 26 percent from just 5 percent a year ago.

IDC said it expects portable PC shipments to increase at an average rate of over 17 percent through 2013 (compound annual growth rate 2009-2013), driving more than 11 percent average growth in total PC shipments and almost 5 percent in shipment value.

“Although mini-notebooks have hurt margins of traditional notebooks, we can expect ultra-thin notebooks based on new low voltage processors from Intel and AMD to somewhat stem the tide,” said Jay Chou, research analyst for IDC’s Worldwide Quarterly PC Tracker.

“By integrating portability, longer battery life, and better multimedia specs and performance, the growth of these ultra thin-n-light systems could give mini-notebooks and traditional premium ultra portables a run for their money,” he said.