Here are a few well known Microsoft software betas, that you can get for absolutely free. Previously some of these betas were only available to Microsoft testers, but they recently released them to the general public. Such as, the Office 2007 Beta 2 and Windows Vista Beta 2.
I highly recommend installing the Windows Vista Beta 2 operating system and on top of that, installing Office 2007 Beta 2. This should only be done on a non-productive system. Windows Vista Beta 2 already has Windows Media Player 11 Beta installed along with Windows Defender Beta 2 and Internet Explorer 7 Beta 2. So there is no need to install them on Windows Vista unless a new build is released. You might want to order Windows Vista Beta 2 on DVD for a small fee, because downloading it can be extremely time consuming and Microsoft servers are under a super high load.
Note: This is beta code and should not be used in a production environment or on a main machine in the home. Beta 2 is intended for developers, IT professionals and technology experts to continue or begin their testing of Windows Vista. Before you decide to use Beta 2, you should feel comfortable with installing operating systems, updating drivers, and general PC troubleshooting. Some risks of using beta operating systems include hardware and software incompatibility and system instability. If you have concerns about installing this beta software on your computer, we encourage you to obtain the final release version of Windows Vista when it is available in 2007.
Office 2007 Beta 2: Homepage | Download
Windows Vista Beta 2: Homepage | Download
Windows Defender Beta 2: Homepage | Download
Windows Media Player 11 Beta 2: Homepage | Download
Windows Internet Explorer 7 Beta 2: Homepage | Download