Microsoft today revealed the option to buy Windows Vista online from the company's recently launched Windows Marketplace. In what may be a first for mainstream OS software, the Redmond-based developer will give access to both 32- and 64-bit upgrade copies of Vista's Home, Business, and Ultimate editions as direct downloads when the OS is officially available on January 30th. The download of a DVD-sized installation is possible through a digital locker, Microsoft says; the service remembers the license for any downloaded software and lets users download software again, even if a catastrophic failure forces a reinstall of the earlier version of Windows.

Simultaneously, the company has revealed its first family licensing plan for Windows. The simply-titled Vista Family Discount will give purchasers of Vista Ultimate in full or upgrade editions the option to buy as many as two copies of Vista Home Premium at $50 each. The upgrade path marks a stark change in the company's approach to home licensing, where the company has previously insisted on individual licenses. Apple has offered five-system licenses of Mac OS X since the introduction of Jaguar in 2002, but has to date only provided physical media for its updates.