Now here is why you want to do this at the start, even if you are not implementing PRO at this time. Even if you never plan on it, one day you might change your mind and the only way to change the VMM Service Account is to uninstall VMM and then reinstall it. Yes you read that right.
As bad as that sounds it really isn’t but it is a pain and it does take time. If you have already installed SCVMM using the LOCAL SYSTEM account you can follow these steps to uninstall SCVMM and reinstall it.
1. Go to Control Panel – Programs and Features
2. Select Virtual Machine Manager 2008 R2 Server (you can leave the Console installed)
3. Click Uninstall
4. During the uninstall you will be prompted to Retain Data, ensure this is selected and continue
5. Once complete, install SCVMM 2008 R2, select the existing SQl Server\Database and this time provide a domain account for the service account.
This will reinstall SCVMM 2008 R2 while still allowing you to retain the existing data and configuration in the SCVMM database. You will have to update the VMM agents on the hosts but to do that simply right-click the host in the VMM console and select Update Agent.