Here is some information about the installation of SCOM 2007 Service Pack 1 on Windows 2008 64bits with a dedicated SQL server also running on Windows Server 2008 64bits.
Is this supported ?
Since end of July 2008, the installation of Operations Manager on Windows 2008 is supported via the installation of several Hotfixes:
First install the following hotfixes available for Windows 2008
Prepare the environment
You will need two Windows 2008 servers (In the case of Single server install, you would need only one, of course). On the first you install the SQL Server 2005, then patch it directly with SP2 (to get support for windows 2008). On top of this, install the latest hotfix rollup package from SQL solution Center. Secure your server according to MS guidelines (see SQL server 2005 Security Best Practices on Microsoft Downloads and use SQL Best Practices Analyzer to help.
Another White paper that I found to be useful is the guide for SQL deployment for Dell PowerEdge (SQL 64bits on 2008)
The second server will host the RMS, and eventually other SCOM roles. You will need the IIS roles, .Net Framework 3, and Powershell.
To get a clear view on what is requested for installing the Reporting services on the SQL backend, check How to install SQL Reporting Services on Windows Vista.
Install Database on SQL server
The first step is to log on the SQL server and install the SCOM Database. This is easily done, just run the prerequisite check, then deselect all roles except the Database.
You will then be prompted for the Management Group Name and the AD group that will host the SCOM administrators.
The next screen allows you to select the target server and port to use.
Finally, you can choose the Database Name (that was not possible with Mom 2005).
(End of Part1)