Just when you thought PC sales would never return, there's a glimmer of hope for a significant PC refresh cycle on the horizon—good news for resellers of Dell, Hewlett-Packard and maybe even Apple.

Bernstein Research is now forecasting a return to PC unit growth next year—with growth of 11 percent in 2010, 13 percent in 2011 and 12 percent in 2012 before returning to a "normal" 10 percent growth rate in 2013.

That forecast aligns with recent comments from Dell and HP. Both companies have said that they are expecting such a refresh cycle to come soon following a few years of delays that correlate with the recession. Most recently, Dell's chief financial officer said even with no change in the economy, a PC refresh would begin in March or April of 2010 simply because PC life spans had already been extended well beyond normal.

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The Bernstein report, which also relies on the research company's own CIO survey, says there will indeed be a "material client replacement cycle," and Bernstein analyst Toni Sacconaghi says the arrival of that cycle is dependent on a larger economic recovery.

"U.S. PC unit growth has historically been correlated with U.S. GDP growth—which suggests a Q4 2009 or Q1 2010 recovery based on U.S. and global GDP forecasts," writes Sacconaghi in the report. "Microsoft's release of Windows 7 in October is also likely to influence timing (likely positive for consumer in late 2009, but negative for corporate until early 2010 as enterprises evaluate the product and wait for SP1 [Service Pack 1] to be released)."

Looking at the trend of the 2001 and 2002 downturn, the Bernstein report notes that corporate PC growth was below trend levels for two years and then rebounded to above trend levels for the next three years.

"We think a similar phenomenon is likely to repeat itself in this downturn," writes Sacconaghi.

"Dell would benefit the most from a PC upgrade cycle, as PCs and related offerings account for 80 percent of total company revenues versus about 30 percent for HP," Sacconaghi notes. "Moreover, Dell's PC business is skewed towards mature corporate markets, which are most impacted by changes in replacement rates."

The refresh cycle won't have as much of an impact on Apple, says Sacconaghi. Rather, pricing actions and acceptance of the Mac platform are bigger drivers for Apple than any corporate PC upgrade cycles.