Apple's iPad should help push tablet sales past netbooks in as little as two years, Forrester analyst Sarah Rotman Epps estimated today. She believes that, even with a conservative estimate of 3.5 million tablets sold this year, the category could grow to 20.4 million by 2012 and make up 18 percent of the market while netbooks would peak at 17 percent. A year later, tablets would overtake declining desktop sales, reaching 21 percent versus 20 percent.