NEW YORK ( TheStreet) -- Microsoft ( MSFT) continued an underwhelming earnings season for the tech sector after market close on Thursday. The software giant brought in fiscal first-quarter revenue of $16.01 billion, down from $17.37 billion in the same period last year, and below analysts' forecast of $16.42 billion. With Microsoft's new Windows 8 operating system set to debut next week, however, the software giant reported deferred revenue of $1.36 billion, taking its non-GAAP sales to $17.36 billion. On a GAAP basis, the Redmond, Wash.-based firm earned 53 cents a share, down from 68 cents a share in the same period last year. Excluding items, Microsoft earned 65 cents a share. Analysts surveyed by Thomson Reuters were looking for earnings of 56 cents a share. Year-over-year, the company's operating income slipped from $7.2 billion to $5.31 billion. On a non-GAAP basis, Microsoft's operating income was $6.66 billion. Investors were clearly underwhelmed by the numbers, pushing Microsoft shares down 2.76% to $28.68 in extended trading. Microsoft CEO Steve Ballmer used the earnings announcement to highlight the forthcoming Windows 8 release. "The launch of Windows 8 is the beginning of a new era at Microsoft," he said, in the company's statement. "Investments we've made over a number of years are now coming together to create a future of exceptional devices and services, with tremendous opportunity for our customers, developers, and partners." The company's Server & Tools business reported revenue of $4.55 billion, an 8% increase on the prior year's quarter, fuelled by double-digit sales growth in SQL Server and more than 20% growth in System Center revenue. Microsoft's Business Division revenue was $5.5 billion, down 2% on the prior year's period. Windows & Windows Live revenue was $3.24 billion, a 33% year-over-year decrease. Online Services was $697 million, a 9% increase on the first quarter of 2011. Entertainment and Devices Division revenue was $1.95 billion, a 1% decrease on the same period last year. The company also reaffirmed its fiscal 2013 operating expense guidance of $30.3 billion to $30.9 billion. -- Written by James Rogers in New York.