Office 2010 marks the first version of Office productivity suite of which the popular applications will be available in both 32-bit and 64-bit versions. And with the availability two system architecture flavors of Office 2010, here’s come the dilemma of which editions, x86 or x64 of Office 2010 to install (check out the leaked Office 2010 official ISO).

To make the decision easier, end-user only need to consider whether 64-bit Office 2010 only if the system has already running 64-bit (x64) OS, such as 64-bit Windows 7. To install a 64-bit version of Office 2010 product, users must have a 64-bit supported operating system on the PC. For 32-bit (x86) OS, the 64-bit Office 2010 option is definitely out.

In addition, installing 32-bit and 64-bit Office 2010 side-by-side natively on the same 64-bit machine is not supported. The restriction applies to both Office 2010 suites or applications, according to TechNet blog. For example, user will be blocked from installing 64-bit Excel 2010 if 32-bit Outlook 2010 is already installed. This also applies to previous versions of Office, so that 64-bit Project 2010 cannot be installed on the same Windows instance as 32-bit Office 2007.

Considering the most modern computers is now powered with a 64-bit capable CPU processors, and 64-bit operating system has started to gaining momentum with the release of Windows 7, many Office users seriously consider to download and install 64-bit Office 2010. Is it a wise and right move?

Microsoft obviously does not think 64-bit Office 2010 is a good bet for average users. According to TechNet document, the main advantage of native 64-bit versions of Microsoft Office products is the ability to take advantage of more virtual and physical memory that can be installed on 64-bit systems (see differences between 32-bit and 64-bit Windows), allowing users to work with much larger data sets than they could previously, and to analyze and solve large computational problems. For example, this additional capacity is needed only by those Microsoft Excel users who require Excel spreadsheets that are larger than 2 gigabytes (GB).

The disadvantage of 64-bit Office 2010 is mainly on add-ins, extensions and ActiveX controls compatibility, which mostly developed for 32-bit Office and will not function in the 64-bit edition. The incompatibility may affect 32-bit versions of programs that interface directly with Office too. Ironically, drivers and applications compatibility issue is also the main reason the delay the popularity of 64-bit Windows OS.

As such, recommendations for which edition of Office 2010 to install from Microsoft 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.

To avoid any possible complication, Office 2010 setup installer has also been defaulted to install 32-bit version of Office 2010 on unified Office 2010 installation DVD or ISO which combines 32-bit and 64-bit versions onto one disc. However, for most Office users who do not use any add-ins or external programs, Office 2010 x64 is the edition to install, as it will definitely be the default version to install in coming years.