We posted earlier about the availability of 64-bit editions of Office 2010. If you are wondering about which edition of Office 2010 to install, the recommendations are as follows:
If users in your organization depend on 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, we recommend that you install 32-bit Office 2010 (the default installation) on computers that are running both 32-bit and 64-bit supported Windows operating systems.
If some users in your organization are Excel expert users who work with Excel spreadsheets that are larger than 2 gigabytes (GB), they can install the 64-bit edition of Office 2010. In addition, if you have in-house solution developers, we recommend that those developers have access to the 64-bit edition of Office 2010 so that they can test and update your in-house solutions on the 64-bit edition of Office 2010.
Office 2010 provides support for 32-bit Office 2010 applications that run on 64-bit Windows operating systems by using Windows-32-on-Windows-64 (WOW64). WOW64 is the x86 emulator that enables 32-bit Windows-based applications to run seamlessly on 64-bit Windows systems. The 32-bit Office client is supported as a WOW64 installation, which is the default installation on 64-bit Windows operating systems. The 32-bit Windows-based applications run on 64-bit Windows, which allows for compatibility with 32-bit Office applications and add-ins.
To learn about 64-bit Office 2010, see the Microsoft Office 2010 Engineering blog article Understanding 64-Bit Office (http://blogs.technet.com/office2010/archive/2010/02/23/understanding-64-bit-office.aspx). For detailed information about the supported operating systems, supported scenarios, setup process, and deployment considerations for 64-bit Office 2010 clients, see 64-bit editions of Office 2010 (http://technet.microsoft.com/en-us/library/ee681792(office.14).aspx) in the Office 2010 Resource Kit (http://technet.microsoft.com/en-us/library/cc303401(office.14).aspx).
For a visual representation of this information, see the 64-bit Client Installation of Microsoft Office 2010 poster (http://go.microsoft.com/fwlink/?LinkId=168620), which includes supported scenarios, deployment considerations, and an overview of the Setup process.
Microsoft is also releasing Microsoft Visual Basic for Applications 7.0 (VBA 7) to work with both 32-bit and 64-bit applications. For more information, see Compatibility Between the 32-bit and 64-bit Versions of Office 2010 (http://go.microsoft.com/fwlink/?LinkId=179546). The article discusses the changes that apply to the 64-bit version of Office 2010 and introduces the new VBA 7 code base.