I have done this few years ago.It's not hard as everyone thinks.I used SQL compare from redgate.

"First, create a new database on the SQL Server 2000 instance using Enterprise Manager, SSMS or writing a CREATE DATABASE [databasename] query.

Launch SQL Compare and choose your SQL 2005 database as the source and specify the empty SQL 2000 database as the target.

SQL Compare will produce a script to CREATE all objects in dependency order, and use syntax that is compatible with SQL Server 2000. Where possible, new features such as CLR assemblies are filtered out because they are incompatible with SQL Server 2000. Sometimes this is not possible, for instance if a stored procedure relies on a CLR function. Since the function cannot be created, the stored procedure cannot be successfully scripted. Analyzing your databases for these conditions first is recommended." from Redgate website.

Thanks,

Rohan