First, the good news... If you use SQL Server Integration Services to load data to or from Excel files or Access databases, then a 64-bit driver is headed your way. This is great news for SSIS users in a 64-bit world. Soon you'll be able to run your packages in 64-bit mode on 64-bit computers, rather...
At run time, you decide the "bitness" of Integration Services package execution on a 64-bit computer by running the 32-bit or the 64-bit version of the dtexec.exe command prompt utility. At design time in Business Intelligence Development Studio, you can also specify the "bitness"...
Herewith my best effort to restate the contents of the Books Online topic, 64-bit Considerations for Integration Services , more simply and cleanly. Unfortunately the BOL topic has become quite messy over time, as one bandage is applied over another, and the costs of localization prevent me from trashing...