The Microsoft Visual Studio 2005 Tools for Office Second Edition (VSTO 2005 SE) redistributable package installs the Visual Studio Tools for Office runtime, which is required to run solutions built using VSTO 2005 or VSTO 2005 SE.
Microsoft Visual Studio 2005 Tools for Office Second Edition Runtime (VSTO 2005 SE) (x86)
Microsoft Visual Studio 2005 Tools for Office Second Edition Runtime (VSTO 2005 SE) (x86)