Microsoft all set to release a near-finished version of the Windows 7 operating system this week, said the program may go on sale by the year-end holiday season. “A holiday release is accomplishable,” Microsoft Senior Vice President Bill Veghte said today in an interview. He declined to say whether the world’s largest software maker could start selling Windows 7 earlier, as some analysts predict. Microsoft is looking to Windows 7 to win back customers that delayed upgrading to Vista, which went on sale in January 2007. Sales of Windows for personal computer dropped 16 percent last quarter, hurt by the recession and demand for cheaper laptops that use an eight-year-old version of Windows.