If you are planning to install SCE07 on a SBS2003 R2 server either for testing or production then you will face many problems, even though Microsoft officially support the SCE07 on SBS2003 R2 but the installation is not that simple. In other words it can said that I’d not implement SCE2007 on top of SBS 2003 R2 to get the benefits of SCE07 while putting yourself in more trouble.
If you are implementing SCE07 on the same server of SBS2003 R2 then you will have to remove the self-signed certificates which are normally installed by Exchnage2003 in a SBS box. So it means you will have to remove all the certificates related OWA, OMA etc.
So in my case I’m implementing SCE07 on a separate Windows Server 2003 Std. which is a member server of SBS2003 R2.
If you want to hear more about SCE07 do visit again, where as SCE07 is System Center Essentials 2007.