As you are likely aware, 64-bit processors are quickly becoming the standard for new servers and desktops. One of the main advantages is that 64-bit systems can use more virtual and physical memory than 32-bit systems, giving users the ability to work with very large documents and data sets. In line with this trend, Microsoft has introduced a 64-bit version of Office 2010 which takes advantage of this additional capacity.
As much as it would appear logical to install the 64-bit version on a brand new machine with a 64-bit operating system, we would strongly recommend users install the 32-bit version (the default installation). The reason for this recommendation is that, currently, many common add-ins for Office will not function in the 64-bit edition.
Office 2010 32-bit lets users continue to use existing extensions to Office, such as ActiveX controls, third-party add-ins, in-house solutions built on previous versions of Office, or 32-bit versions of programs that interface directly with Office. The 32-bit version of Office 2010 provides the same functionality and is also compatible with 32-bit add-ins.
This being said, if your organization has some Excel users who work with spreadsheets that are larger than 2 gigabytes (GB), then they may be a good candidate for the 64-bit edition.
Also, in case you were wondering, it is not possible to have any of the 32-bit Office 2010 applications installed when you install the 64-bit Office.
The D&A Team