For all those out there looking for the Pre-requisites for Exchange Server 2007 as a simple checklist to follow, here they are. General Domain Level Requirements At least 1 Windows 2003 Server Domain Controller & Global Catalogue Server Windows Domain & Forest in Native Mode Edge Transport Server (Preferably a WorkGroup Server NOT Domain Member with 2 NIC Configuration) Windows 2003 R2 SP1 or above Domain Suffix Appended to the Server Name (Computer Name / Change / More) .Net Framework 2.0 .Net Framework 2.0 SP1 .Net Framework 3.0 (recommended for Exchange 2007 SP1) .Net Framework 3.0 SP1 Windows Powershell 1.0 Active Directory Application Mode (ADAM installed from ADD/Remove Programs) Hub Transport Windows 2003 R2 SP1 or above Domain Member .Net Framework 2.0 .Net Framework 2.0 SP1 .Net Framework 3.0 (recommended for Exchange SP1) .Net Framework 3.0 SP1 Windows Powershell 1.0 IIS (ONLY required for centralized remote management through Management Consoles) Client Access Server Windows 2003 R2 SP1 or above Domain Member .Net Framework 2.0 .Net Framework 2.0 SP1 .Net Framework 3.0 (recommended for Exchange SP1) .Net Framework 3.0 SP1 Windows Powershell 1.0 IIS (Required) RPC/HTTP Proxy Service (Required for Outlook Anywhere) Mailbox Server Windows 2003 R2 SP1 or above Domain Member .Net Framework 2.0 .Net Framework 2.0 SP1 .Net Framework 3.0 (recommended for Exchange SP1) .Net Framework 3.0 SP1 Windows Powershell 1.0 IIS (ONLY required for centralized remote management through Management Consoles) Unified Messaging Server Windows 2003 R2 SP1 or above Domain Member .Net Framework 2.0 .Net Framework 2.0 SP1 .Net Framework 3.0 (recommended for Exchange SP1) .Net Framework 3.0 SP1 Windows Powershell 1.0 IIS (ONLY required for centralized remote management through Management Consoles) MS XML 6.0 Parser Libraries Windows Media Player 11 Runtimes I hope that someone out there wil find this post helpful, if you find any variations / requirements I have skipped out above, please feel free to post & share the knowledge of the same with others.