Operating systems are big business. But just how big you ask? According to research firm Gartner, sales of server and desktop operating systems totalled nearly $30.4 billion in 2010 alone. “As the global economy recovered, worldwide operating system (OS) revenue totaled $30.4 billion in 2010, a 7.8 percent increase from 2009,” explains Gartner. “Among client OSs, Mac OS was the fastest-growing subsegment in 2010 as the unit shipments of Mac desktop/laptop devices saw strong sales, although from a much-smaller basis. Windows client was still the largest client OS segment, with high-single-digit growth, particularly driven by adoption of Windows 7 and the imminent end of life (EOL) of Windows XP.” Oracle saw the largest percentage-growth year-over-year thanks to its acquisition of Sun Microsystems. Analysts are expecting the operating system revenues to continue to rise in 2011.