"ISA Server 2006 makes it easier to provide security for corporate applications accessed over the Internet by pre-authenticating users before they gain access to any published servers, inspecting even encrypted traffic at the application layer in a stateful manner, and providing automated publishing tools. In addition, by providing HTTP compression, caching of content including software updates, and site-to-site VPN capabilities integrated with application-layer filtering, ISA Server 2006 makes it easier to securely expand corporate networks. ISA Server 2006 also makes it easier to manage and protect your network with a hybrid proxy-firewall architecture, deep content inspection, granular policies, and comprehensive alerting and monitoring capabilities.

System Requirements
Supported Operating Systems: Windows Server 2003; Windows Server 2003 Service Pack 1
• A personal computer with a 733-megahertz (MHz) or higher Pentium II-compatible CPU.
• Microsoft Windows Server 2003 operating system with Service Pack 1 (SP1).
• 512 megabytes (MB) of memory.
• 150 MB of available hard disk space. This is exclusive of hard disk space you want to use for caching.
• One network adapter that is compatible with the computer's operating system, for communication with the Internal network.
• An additional network adapter for each network connected to the ISA Server computer.
• One local hard disk partition that is formatted with the NTFS file system

Warning: Do not install ISA Server 2006 Standard Edition on a multi-processor computer with more than four processors."