http://www.microsoft.com/office/2010/en/download-office-professional-plus/default.aspx
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You need to have a Windows Live ID.(MSN Hotmail or MSN Messenger ID is your windows Live ID).
you need to register to begin download and its simple and easy. Its download size is about 700 MB and you need 3.5 GB of available disk space. The download is resumable, so no need to be afraid of being interupted while downloading.
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You can upgrade the current installed MS Office version to Office 2010 beta. You will also have option to customize installation so that you may use Office 2010 beta with your current installed version at the same time.
You have to require onlin activation after installation. This Office 2010 beta version will expire in October,2010 and you have about 1 years to use it.So why are you waiting for ???. Download it and realize the new features integrated with the new version.