release management - How to select the architecture to download?

I'm a completely new user of Linux and since my computer is not a good machine I wanted to install 32 bit OS, I downloaded ubuntu desktop for 32 bit but when I check in system settings under details it says my OS type is 64 bit, I downloaded it from the site http://www.ubuntu.com/download/desktop choose Ubuntu 12.04 LTS and set it as 32-bit (machines with less than 2GB RAM).