All you have to do is 'explore' your Fable discs until you find the file 'textures.big'. Then copy it to the folder:
C:\Program Files\Microsoft Games\Fable - The Lost Chapters\data\graphics\pc
Just in case, by 'explore' I mean insert the disc, stop it if it tries to 'autorun', click on 'My Computer', then right click the drive with the Fable disc and click the 'explore' option. Once you find the file you want you have a couple options.
I prefer: highlight the file, click edit, then copy to folder, a window asks where to copy it to, choose the path above.
Good luck,