Quote MS: "In the Release Candidate build, we recommend you do not to install on a Domain Controller. While the Setup User Interface does the correct thing by suppressing the Standalone option, after the installation is done and the RC is fully installed, it is actually a Standalone install and not a farm install. Although you are not technically blocked, the install will not work since SQL Express 2008 is not supported on a Domain Controller."
Because SQL Express 2008 is not supported on a DC, if the installation detects you are installing on a DC, the selection page where you can choose between a Stand-Alone and Complete installation is removed. Unfortunately the Stand-Alone option is the default selected option, causing you to end up with a Stand-Alone installation anyways and no way to get around this via the GUI :-)
The best way to install SharePoint 2010 RC on a domain controller is by using an scripted installation.
- Extract the installation file by executing <filename> /extract:<folder name>
- Open a Windows Explorer and create a file called config.xml.
- Open the config.xml file and paste in the part below
- Change the <PID KEY> into your own product key and the install folder
- Save the file
- Start a command prompt and browse to the folder
- Run "setup /config config.xml"
- SharePoint 2010 RC is now being installed as a Complete installation!
Have fun SharePointing!
<Setting Id="LAUNCHEDFROMSETUPSTS" Value="Yes"/>
<Setting Id="SETUPCALLED" Value="1"/>
<Setting Id="OFFICESERVERPREMIUM" Value="1" />
<Logging Type="verbose" Path="%temp%" Template="SharePoint Server Setup(*).log"/>
<PIDKEY Value="<PID KEY>" />
<Setting Id="SERVERROLE" Value="APPLICATION"/>
<Setting Id="USINGUIINSTALLMODE" Value="0"/>
<Setting Id="SETUP_REBOOT" Value="Never" />
<Setting Id="SETUPTYPE" Value="CLEAN_INSTALL"/>
<INSTALLLOCATION Value="D:\Program Files\Microsoft SharePoint" />
<Display Level="Basic" CompletionNotice="Yes" AcceptEULA="Yes" />