Total Network Inventory: Professional PC audit and network inventory management software - fits best for a for companies of all sizes. Free for 60 days.
Network Inventory Advisor - Network Inventory Advisor audits all network software and hardware simply and efficiently
Inno Setup - Inno Setup is a free installer for Windows programs.
Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
Advanced Installer - Advanced Installer is a Windows installer authoring tool for installing, updating, and configuring your products safely, securely, and reliably.
Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
InstallShield - If your software targets Windows, InstallShield is your solution.