Microsoft recently made the successor to the popular Microsoft Office 2007, Office 2010, open for public beta. Available for both 32 bit and 64 bit systems, this new package is poised to become the standard once it moves on to its final stage.
To download the beta, you must be subscribed to MSDN (Microsoft Developer Network) or TechNet.
Be advised that it is not recommended to access the beta across P2P networks, with obvious concerns about using such services for the exchange of copyrighted software.