Here’s an interesting nugget.  If you use a “least privileges approach” in setting up MOSS with the full array of service accounts (and you should), there are several permission changes that you need to make to DCOM config in order to make some event log errors go away.  This much is not news.

BUT, in R2 of Server 2008, the most important one of these is locked down and won’t let you change it.  If you try to change the “IIS WAMREG admin Service” in R2 you’ll see a grayed out screen like this:

Even if you’re a full admin, you’re still locked out.  It turns out you have to into regedit and give yourself permissions to the corresponding registry key just to be ABLE to modify it in DCOM.  I found full instructions to fix it up in this blog post: http://www.wictorwilen.se/Post/Fix-the-SharePoint-DCOM-10016-error-on-Windows-Server-2008-R2.aspx

I had to pass this on.  Because I we’ll be running into this a lot as we get involved with MOSS installs on Server 2008 R2 servers.