Here are the following steps I used to install OSS B2TR
1. Start with a fresh installation of Windows Server 2003. Or uninstall all Office production from a machine with a B2 installation and clear out all Office related registry entries
2. Install OSS B2
3. Run the Configuration Wizard after the installation is complete
4. After the Configuration Wizard is done, make sure the SharePoint Central Administration tool loads. If the configuration is complete, do not add any Web Application or Site Collections. If you receive this error during the installation of Office SharePoint Server 2007:"The language is not supported on the server"It means that you have uninstalled a previous version (or the same version) of Office SharePoint Server on the server, and it has taken the Server Language reg value with it!In order to fix the problem, you need to restore the Server Language registry value by creating the following .reg file (open notepad and paste the following):Windows Registry Editor Version 5.00[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\12.0\ServerLanguage]"1033"=""
5. Go into the Service node of the MMC and stop and disable the Office SharePoint Search and Window SharePoint Search.
6. Once the search services are stopped, starts the WSS B2TR installation (filename: WSSv3b2tr-kb000000-x86-fullfile-en-us.exe). Once that is complete, and if you have OSS installed, a dialog box should prompt the user to upgrade at least one more product on the server.
7. After completing the WSS B2TR then start the OSS B2TR installation (OfficeServerb2tr-kb000000-x86-fullfile-en-us.exe).
8. Once complete, the configuration wizard should start and reconfigure OSS. 9. Once complete, you should be able to setup a Default Web Application and the Default Site Collection as well as the Shared Service Provider.
Hope this helps!!!!