Technically this should work with a few tweaks but I have not tried it nor would I recommend just doing it in a live environment. Can you do it in a lab first?
To have the 2008 machine be a DC, you have to upgrade the schema before, otherwise just
add it as a member server. <a href=”http://technet2.microsoft.com/windowsserver2008/en/library/15883a88-9a03-46da-8c7d-bc4ed84ff3021033.mspx?mfr=true”>See this page for more information.</a>
Here is a list of the schema updates needed:
They can all be grabbed from here:
<a href=”http://technet2.microsoft.com/windowsserver2008/en/library/9824091d-e659-4619-8051-1c2aa2c2198e1033.mspx?mfr=true”>Via microsoft.</a>