The number of homes sold in Northern Virginia rose 10 percent in February, as buyers continued to take advantage of falling prices. During the month, 1,067 homes were sold in the area, which includes the cities of Alexandria, Fairfax and Falls Church as well as the counties of Fairfax and Arlington, according to Rockville-based market research firm Metropolitan Regional Information Systems Inc. In the same month in 2008, the number of homes sold was 969.