It seems that by default SharePoint 2007 has some DCOM/IIS related issues on Windows Server 2008 R2.  I've run into this error multiple times on multiple servers:

EVENT ID: 10016
SOURCE: DistributedCOM
LEVEL: ERROR
The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID

{61738644-F196-11D0-9953-00C04FD919C1}

and APPID

DCOM. I'm sure it sounded like a good idea at the time, but in the real world it generates a lot of headaches. Here's some common DCOM, COM+ and WMI errors along with some fixes. There's also some scripts and registry keys at the end of article to help automate the fixes.

CoCreateInstance Errors