Microsoft has released a beta version of Office 2010. This beta version is freely available for downloading and is valid up to October 2010. At that time,you will have the option to purchase the full version or uninstall the beta.
This version includes Word, Excel, PowerPoint, Access, Publisher, and Outlook and can be downloaded from here .
Lighter users may choose to download 
This version includes Word, Excel, PowerPoint and Outlook and can be downloaded using the new Click-to-Run. Click-to-Run allows you to start using some aspects of Office while the rest of the Office suite is being downloaded in the background. This can be downloaded from here.