Installing for AutoCAD 2007 on a 64-bit system can be tricky because AutoCAD 2007 was originally designed as a 32-bit application. Modern 64-bit Windows versions usually handle these through an "x86" (32-bit) compatibility layer, but the CivilCAD installer must specifically match the version of AutoCAD you have installed. Compatibility Overview
CivilCAD 2007 extends the basic functionality of AutoCAD 2007, 2008, and 2009 with specialized tools for terrain modeling and site design: civilcad para autocad 2007 64 bits
An add-on by ARQCOM specifically built for the AutoCAD 2007/2008 environment. System Architecture: CivilCAD Installing for AutoCAD 2007 on a 64-bit