Office for Mac 2008 Installer will install both sets of code (Intel/PPC) regardless of what machine type you are installing onto. This is common behavior for the Apple installer and is important in the cases where you are installing onto a drive that might be shared with Intel/PPC computers (such as an external travel drive, Network Boot servers, and Shared Network Application Folders).
According to developer Matt Centurión:
I’d like to tell you that it . . .
Continue Reading: Office 2008 Installs code for both Intel and PPC