Microsoft Office 2010 Beta comes in both 32-bit and 64-bit versions and this is the first time that a 64-bit version of Office has been available. 64-bit processing brings some advantages but are they outweighed by the disadvantages of being on the bleeding edge of technology?

If you’re running 64-bit Windows Vista or Windows 7 (or Server 2008 or Server 2008 R2), you can choose whether to the install 64-bit version of Office 2010 beta. (It is not compatible with 64-bit Windows XP.)

The advantages of the 64-bit version are that it lets you use additional memory installed on your computer – for example Excel 2010 workbooks can be bigger than 2GB. Project 2010 can work with very large projects consisting of many sub-projects. You also get enhanced security through Data Execution Prevention (DEP) by default.

But, not many people will actually need Excel Workbooks bigger than 2GB. If you ever made one, you could not store it in SharePoint – 2GB is SharePoint’s limit for any file – and you could not share it with anyone who wasn’t running 64-bit Office 2010 because they wouldn’t be able to open it.

Access databases with their code removed (split data & code in separate files) can’t be shared between 32-bit and 64-bit versions of Office and any VBA code may not be compatible between 32-bit and 64-bit versions, particularly where the code declares API calls to Windows or uses the new LongLong or LongPtr data types introduced in the 64-bit version.

Graphic elements may render more slowly in the 64-bit version of Office because 64-bit CPUs may lack MMX support for multimedia and communications.

The biggest problem by far is that ActiveX controls Add-Ins and COM DLLs written for 32-bit Office will not work with the new 64-bit version. Microsoft are due to release a new VSTO (Visual Studio Tools for Office) runtime which will bridge this gap for DLLs and Add-Ins written using VSTO but it isn’t available yet. Other manufacturers will have to test, possibly change, and re-issue their DLLs and Add-Ins in 64-bit versions to get them to work.

There are yet more problems if you try to work with web based solutions that use ActiveX controls. For instance SharePoint uses an ActiveX control to render SharePoint lists in Datasheet View. This view is not supported if you install the 64-bit version of Office 2010.

All in all, the 64-bit version of Office is useful to very few people and has many limitations. The vast majority of people will be much better off sticking to the 32-bit version.