Typically, an operating system upgrade offers users the choice between an in-place migration of the machine -- including installed applications and all data -- and a fresh installation, which overwrites the hard drive's contents. When Microsoft launched Windows Vista in January 2007, for example, it offered people then running XP those upgrade paths.

Smith and other analysts applauded Microsoft's decision to not provide in-place upgrades from XP to Windows 7. "I'm not a big fan of them," said Smith. "They're tough enough from one version to the next, and from two versions [behind], it would be pretty challenging, technically."

, formerly an analyst at , and now a vice president of mobile strategy with JupiterMedia, agreed. "For most end users, it will probably mean that they end up with a more reliable installation," he said.

Microsoft benefits, too. "It makes life a lot easier for Microsoft by not having to support an XP to Windows 7 transition," said Gartenberg. "It means that it's something they can get out the door earlier."

Microsoft has been aggressively pushing Windows 7's timetable. Just two weeks after it launched the first -- and in the end, the only -- public beta of the new operating system, the head of Windows development said the company is moving