You should try uninstalling RTW and then reinstall. When the installer asks you were to put it, don't put it under the "Program Files" directory (the location doesn't really matter - I used "C:/My Programs/The Creative Assembly/Rome - Total War"). Remember where you put it, wherever that is. Then install the patches, which should automatically find it, then install EB (remember to change the install location to the same place you put RTW when installing EB).