Best Buy Co. boosted its second-quarter earnings by 10 percent with strong sales of entertainment software and digital products. Best Buy, based in Eden Prairie, Minn., earned $85 million, or 39 cents a share, in the quarter ended Sept. 1, compared with $77 million, or 36 cents a share, a year earlier. Analysts surveyed by Thomson Financial/First Call expected 38 cents. Shares of Best Buy, the nation's largest consumer electronics retailer, rose $1.37, or 3 percent, to close at $49.37 in trading Tuesday on the New York Stock Exchange. Second-quarter sales rose 31 percent to $4.16 billion, from $3.17 billion. The increase reflected the addition of 66 Best Buy stores over the past year to bring the total number of stores to 439, as well as sales from about 1,300 Musicland Group stores, including Sam Goody, Media Play, On Cue and Suncoast. Best Buy completed the acquisition of Musicland in February.