Full-text searching and/or word indexing

Hi,

I want to use full text searching on my PostgreSQL 7.0.2 database. Ok, to be
exact I want to somehow be able to type the word 
alien and get a record set containing "Alien", "Alien 3" and "Alien
Resurection". ( "Aliens" could should also be returned but that would
probably take more time, so I`ll go with plain hits to begin with. )

How can this be done? If it`s not possible using just PostgreSQL, what is
the best tool for the job? ( I`m using Python and Zope for the rest of the
project, so if anybody has solutions using these tools that would be
perfect. )

Thomas