From author's site:

Inno Setup is a free installer for Windows programs. First introduced in 1997, Inno Setup today rivals and even surpasses many commercial installers in feature set and stability.

Key features:

* Support for all versions of Windows in use today: Vista, XP, 2003, 2000, Me, 98, 95, and NT 4.0. (No service packs are required.)
* Extensive support for installation of 64-bit applications on the 64-bit editions of Windows Vista, Windows XP, and Windows Server 2003. Both the x64 and Itanium architectures are supported. (On the Itanium architecture, Service Pack 1 is required to install in 64-bit mode.)
* Supports creation of a single EXE to install your program for easy online distribution. Disk spanning is also supported.

From author's site:

The installation builder is a simple SDI application with a tabbed form where you can enter all the information needed by the setup program. For example: add files, assign shortcuts and other setup specific variables.
You can also use the wizard that will guide you through the necessary steps of creating a setup program for your software product.

The application has 4 tab-pages:
> General, where you can enter application name, company name and so on.
> Files, this is where you specify all files, which need to be distributed.
> Shortcuts, specify shortcuts in the program folder (start menu).
> Output, the final step where you enter the output directory.