Prepare and Backup
1. Backup all SQL databases
2. Make a List of Web applications and related IIS site, Application Pool and Content Database.
3. Disable enterprise feature at Farm Level, for each web application and for all sites
4. Note which server is hosting SharePoint Central Administration and confirm that there are no pending or failed backup/restore or upgrade timer jobs.
5. Make a list of every server that host SharePoint Central Administration.Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\12.0\WSS\ServerRole and record the value. Repeat these steps for each server with MOSS installed
6. Backup the 12.0 hive from the registry (Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\12.0 Right Click on 12.0 and click Export)
7. Now edit the registry key by renaming the dsn key. Navigate to [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\12.0\Secure\ConfigDB\dsn] Right click on dsn and click rename
8. Purge the old configuration wizard logs. From command prompt type "cd "%programfiles%\common files\microsoft shared\web server extensions\12\logs" Then type del psc*.log
9. Check to see if you have installed any language packs and uninstall them.
Uninstall Enterprise Edition
10. Now uninstall MOSS Enterprise from Add/Remove Programs. This will uninstall MOSS completely from your machine but will not delete any of your data.
11. Reboot your server
Install Standard Edition
If you have more than one MOSS server repeat these steps for all servers in the farm.
Now that all servers have had MOSS uninstalled from them and have been rebooted you need to install MOSS 2007 Std. You will perform the following steps on one server at a time. Start with the web front end server that previously hosted Central Admin and then you may do all additional servers in any order. Perform only on one server at a time. If any server fails resolve the issue before continuing to the next server.
1. De-Select the box for running the Configuration Wizard and click Close.
2. Now install any necessary language packs on the server. Instructions found here.
3. Once all servers have been installed return to your original web front end server which will host SharePoint Central Administration.
4. Click Start > All Programs > Microsoft Office Server > SharePoint Configuration and Technologies Configuration Wizard.
5. Click Next at the Welcome screen.
6. At the warning message click Yes.
7. At the Completing SharePoint screen you should see your database and database server listed. Click Next.
8. You will see a warning message reminding you to install MOSS on all servers in your farm before proceeding. Ignore this warning message and click Ok
Post Configuration
Now find out what your servers search topology is.
1. Go to SharePoint Central Administration and click the Operations tab
2. From Topologies and Services click Services on Server
3. If the Office SharePoint Server Search is started from the command line on this server you need to run the command stsadm -o osearch -action start
4. Recreate Web application Using the Existing IIS site and Application Pool and attach the content databases to them
