Microsoft has posted a page to its Windows Vista site that sorts out upgrade options for users of Windows 2000 and Windows XP.
"Certain legacy OSes require a full system installation while others will allow for an in-place upgrade," said Vista program manager Nick White on the team's blog. "Depending on where you're coming from and where you're going, you should determine which scenario applies to you."
A chart on a page titled "Upgrade Planning for Windows Vista" details upgrade paths, and notes who will be able to install Vista overtop an existing OS and who will have to scrub their hard drives before switching to the new operating system.
According to the chart, only Windows XP Home, XP Professional, XP Media Center, and XP Tablet PC users will be able to upgrade in-place, and then only to specific versions of Vista. Windows XP Professional, for example, will be able to do an in-place install only to Vista Business and Vista Ultimate. To upgrade to Vista Home Basic or Vista Home Premium, a Windows XP Pro user would first have to back up all files; after adding Vista, he would need to reinstall all applications and restore the saved data files.
Microsoft also noted that anyone using a Windows prior to 2000 can only upgrade to Vista with a clean install and using a full copy of the operating system, as opposed to an upgrade edition.
Although Microsoft outlined Vista's editions in February, it has not set prices for full editions or discussed upgrade costs.