Netbooks are about to face stiff resistance from many of the companies that touted them just last year, Avian Securities said in a research note on Tuesday. Analysts at the firm still expect netbook sales to rise, from 37 million in 2009 to 47 million this year, but that notebooks will leap from 140 million to 180 million in the same span. The fourfold larger growth would come from PC builders trying to drive customers to more expensive regular notebooks after frustration at the low profit margins of netbooks.