I want to say first that this is not the only way of setting up such a service. There are many ways of achieving this goal but this is the way I took. I do not issue any guarantee that this will work for you!
Setting up Outlook Anywhere on newly installed exchange 2007 server, running windows 2003 64bit.
Go to control panel – Add and Remove Programs – Add/Remove Windows Components – Networking Services – Select Details – Click the “RPC over HTTP Proxy” check box. [ok]
Open Exchange Management Console – Expand Server – Exchange Server 2007 Client Access servers – to be completed soonest.