Just a quick note on a little error I had installing OCS 2007. We have a lot of users that are set up to run services for applications – as such we have a fairly tightly controlled group policy regarding the permissions required to run as a service. This causes the error above to occur because the newly created users aren't given permissions to run a service. The solution is to add the newly created users to our Application Service group.
I added the RTCService user after the first installation failed, and ran again. It will fail a second time because the RTCComponentService is not created at the time the RTCService user causes the installation to fail the first time. Add the RTCComponentServiceto the group and it will install without any issues.