Here’s a quick overview of the Exchange 2007 requirements :

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