Microsoft next month plans to release a toolkit to help business customers begin testing their existing applications for compatibility with Windows 7.

In a virtual roundtable Microsoft hosted this week to field questions about Windows 7, Mark Russinovich, a Microsoft technical fellow, said Microsoft would release the Application Compatibility Toolkit to "support Windows 7 pre-releases" in "the April 2009 time frame."

Microsoft also will release another version of the toolkit to correspond with Windows 7's final release to manufacturing, which is expected later this year. Microsoft has said it is on track to release Windows 7 three years after Windows Vista, which was released to business customers in November 2006 and consumers in January 2007.

Microsoft used to release Windows application-compatibility toolkits after the general release of the OS. However, Microsoft released the application-compatibility toolkit for Vista at the same time the OS was made generally available to give customers more time to begin testing applications Still, businesses found application compatibility one of several problems they encountered with Vista deployment, and many opted to wait until Windows 7 before upgrading from Windows XP or their existing version of Windows.

Though companies will have a considerable amount of time to test existing applications for compatibility with Windows 7 ahead of its release, it should be a less painful process if they've already done Vista testing. According to the roundtable transcript, applications compatible with Windows Vista should already be compatible with Windows 7 since the two OSes "share similar design frameworks."

"The [OS] kernel ... is updated with Windows 7, but is based on the same underlying architecture [as Vista]," according to the transcript.

However, Windows XP and Windows 7 are built on different design frameworks, so "the levels of application compatibility are not the same," it said. Businesses will likely need more time to ensure applications are compatible with Windows 7 before beginning a broad deployment.

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