need i686 kernel iso

Windows-XP32 on my circa-2005 Toshiba laptop has finally died and cannot be recovered. I would like to try Ubuntu as a replacement (new user). My problem is that the computer I need to use to download the ISO file runs an AMD-64 CPU. My laptop (barely) runs on an Intel Centrino CPU (2GB RAM). The first file I tried to boot (downloaded from Ubuntu Desktop download page,) did not not load, telling me that I needed an i686 kernel ISO. How can I select the correct file. I noticed that my first ISO download seemed to automatically detect and select the AMD version, but I had to try it to get to this point. Where do I go from here ?