Some say you need to go through all the updates, one by one. I've always just found dropping the 1.7 exe in the CoD4 file and have not had issues (Not sure about other versions.. CoD4 only). As Crunch is saying, you may have to have admin rights. All the files are in XI download section though.
Once you get it up and running normal. Copy the CoD4 file and save to disk or email. You can avoid these issues. At the very least, save the 1.7 exe and profiles. Mods will always reinstall upon joining any server.
Edit, Install PunkBuster files too if needed. Even though it's not supported anymore, some servers still require it.