If you are considering the deployment of a 64-bit version of Microsoft Office 2010, it is important to understand the differences between the 32 and 64-bit versions, and be aware of the deployment considerations.
See the following blog posts and TechNet articles for related information:
Microsoft Office Product Development Group blog post, Understanding 64-Bit Office
64-bit editions of Office 2010
Blocking and nonblocking Office applications in 64-bit installations
The images below are excerpts from a visual representation of the 64-bit Client Installation of Microsoft Office 2010, which can be found at http://go.microsoft.com/fwlink/?LinkId=168620.