Once you've completely removed RTW from your system you should have no problem re-installing it and afterwards installing EB as well. EB is really a very simple mod to install..all you have to do is point it towards the root directory of your choice and the installer takes care of everything else. After you've made certain that RTW/EB has been uninstalled and your system is completely clear as suggested in the post above . I would recommend one more step..Clear your registry of any RTW keys that were not picked up by the uninstaller....If you are not comfortable or not sure how to work with Regedit get yourself a Registry Cleaner because if you don't know what your doing in there and happen to delete the wrong key you can seriously mess up your system. Here's a link to a program that has a registry function.

http://www.filehippo.com/download_ccleaner/

Once your system is completely clean of your previous install...you should have no problem reinstalling RTW and then EB. My last suggestion would be to make a copy of your vanilla installation and not install any mods on that. Install mods only on the copies.