Question : Upgrading Exchange from 5.5 to 2003

Forestprep will not execute on a 2003 R2 x64 server preparing to migrate Exchange 5.5 on a 2000 32 bit server. Adprep Forest and domain were run prior to promoting the 2003 server to PDC.  Here is the error and subsequent information:
To update the domain functional level, the domain controllers in the domain must be running the appropriate version of Windows.

Current domain functional level: Windows 2000 Native

The following domain controllers are running earlier versions of wndows:  
Windows Server 5.0 (2195)

Original configuration:  Windows Server 2000 running Exchange 5.5  Added Server 2003 x64 in order to upgrade Exchange to 2007.

Adprep forest and domain run with R2, and 2003 server added as PDC.  Additional items performed:
DNS, SMTP, WWW Service, Certificate server, .NET Framework 2.0, and ASP.
- Domain level raised.
- Operations masters changed (RID, PDC, Infrastructure).
- Installed 4 Windows Critical updates on 2K3server.
- Domain and trust operations masters changed to 2K3server

What am I missing here?

Thanks folks

Answer : Upgrading Exchange from 5.5 to 2003

Your 2007 version is SP1, as evidenced in the name    "Ent_2007w_SP1"

Just download the x86 SP1 version to use for forestprep and you'll be all set.