Make sure you note which version you download of the Office 2010 Beta (32-bit or 64-bit), as there do not seem to be any distinguishing marks. If you try to install a 64-bit version of Office on a 32-bit machine, you will not receive any warning, the files will be extracted but then the install never starts. It may leave you wondering what has happened. The same thing goes for SharePoint 2010, by the way, if you try to install the Beta in a 32-bit environment.