I NEED HELP OPENING THE FILES!!! PLEASE!

I am running Mac OS X Lion 10.7.1. I have downloaded the razor1911 version of the sims, but haven't cracked it yet, I have also downloaded the ultimate fix from the website.
I also downloaded world adventures from the website, ( in .rar format) and i used stuffit expander to open. I can't get the installer to work. It says " we could no verify the integrity of this installer". Please help! I don't know what to do. I just want to get The sims 3 with the world adventures and high end loft stuff. I read on the ultimate fix that i have to have either late night or generations, so i plan on generations as well. Im trying to get all the expansions and stuff packs downloaded before i work on the ultimate fix installation guide, but i can't seem to get any of the expansion packs to install!!! What do i do? please please help!!