Fueled by a growing interest in tablet computers, nearly half a billion PCs will be sold to consumers in the US between now and 2015, according to a new report by Forrester Research.

Over the next five years, PC unit sales across all form factors ? desktops, notebooks and laptops, tablets, and netbooks ? will increase by 52 percent, as outlined in the Forrester report, "The US Consumer PC Market In 2015." Data in the report is based on Forrester's latest five-year ForecastView for the personal computing and eReader markets in the US.

Despite an ongoing industry debate about how to define tablets, Forrester believes they should be classified as a form of personal computer. Tablet sales in the US will go from a modest 3.5 million units in 2010 to 20.4 million units in 2015, a 42 percent compound annual growth rate. Starting in 2012, tablets will outsell netbooks, and by 2014, more consumers will use tablets than use netbooks. In 2015, tablets will constitute 23 percent of PC unit sales.

"Tablet growth will come at the expense of netbooks, which have a similar grab-and-go media consumption and Web browsing use case as tablets but don't synchronize data across services like the iPad does," said Forrester Research Analyst Sarah Rotman Epps. "Consumers didn't ask for tablets. In fact, Forrester's data shows that the top features consumers say they want in a PC are a complete mismatch with the features of the iPad. But Apple is successfully teaching consumers to want this new device."

While desktop sales will slide over the next five years, going from 18.7 million units sold in 2010 to 15.7 units in 2015, desktops will continue to play a relevant role in the market, buoyed by consumers' desire for processing-heavy activities such as gaming and watching and editing HD and 3D video and graphics.

By 2015, Forrester forecasts the US PC market will break down as such (based on percentage of units sold in 2015): notebooks (42 percent), tablets (23 percent), desktops (18 percent), and netbooks (17 percent).

"Product strategists should align their offerings to capitalize on these market shifts, with chipsets, displays, accessories, software, and content that anticipate the growth of tablets and the continued relevance of traditional PCs," said Epps.