Moving your database shouldn’t be all that hard. It sounds like you are planning on moving the application from the current server to a third server which makes it easier to do.
1. Install SQL 2000 on the new server. You will want to patch it to the same patch level that the current server is running or higher. I recommend that you patch the server to the highest patch level, but check with the application vendor to be sure. You can use the SQL Server Version Database to find the correct patches to install.
2. Use sp_help_revlogin on the old SQL Server to script out all the logins and passwords are recreate them on the new SQL Server.
3. Turn off the application on the old server (stop the services, turn off the web server, etc).
4. Detach the database from the old SQL Server using either SQL Server Enterprise Manager or the sp_detach_db stored procedure. If using the SQL Server Enterprise Manager right click on the database and select detach.
5. Copy the physical database files from the old SQL Server to the new SQL Server.
6. In SQL Server Enterprise Manager right click on the databases container and select Attach database. Navigate to the correct folder where you placed the MDF file and select it. Ensure that the path which displays to the LDF is correct. If it is not, then correct it. Press OK when ready.
7a. Install the application on it’s new server. When it asks for the database server give it the name of the server to just attached the database to. The username and password will be the same.
7b. If you are not moving the application to another server then you will want to find the configuration files for the application and edit them so that they point to the now remote SQL Server. You may need to call the application vendor in order to find these.