setup.exe does nothing, or throws “The version of this file is not compatible with the version of Windows you’re running.”The problem was that AutoCAD 2008 was natively a 32-bit application. While Windows 7 was excellent at backward compatibility—running 32-bit apps on a 64-bit OS via the WOW64 (Windows 32-bit on Windows 64-bit) subsystem—it could not magically transform the software into a 64-bit application. This meant that even on a powerful new workstation, AutoCAD 2008 was capped at 2GB of memory address space (or 3GB with a specific boot switch). For architects working on massive civil plans or 3D models, this was a critical bottleneck. The search for a "64 bit" version of the 2008 software is, historically, a search for something that never officially existed. It represents a user base desperate to hold onto their favorite tool while embracing modern hardware speeds.