This project is hosted by Sourceforge and it can be found at http://sourceforge.net/projects/prodevtools/
If you want to install ProDT as plugins in your existing Eclipse installation (3.3 or above), you should download ar.com.tadp.prolog_0.1.1.zip
If you don't know much about Eclipse, but want to start using it, you can download:
In any case, you should follow the corresponding installation and configuration guides.