It can be added as a domain member, but no other roles for Windows servers. Id recommend running it with bare minimum GPOs pushed to it. Its quite "fininky" when it comes to CUEAC. All updates really should be approved prior to install (For example Service packs may turn on Windows Firewall by default). I have run CUEAC fine as a workgroup server with no issues, but we all understand why Windows Admins want "control" of the box for security, management, etc.
