Do not download "ttw.rar" from unofficial third-party sites, as it often contains pirated game assets. The official method requires you to use the TTW Installer on your own legal game copies.
: You must own legal, clean installations of both Fallout 3 (GOTY) and Fallout: New Vegas (Ultimate Edition). ttw.rar
If you have downloaded this archive, follow these general steps: Do not download "ttw