Gabriel,

>Can anyone tell me wich is the best free programmer that
>  covers 16C84, 12C5XX, and 16C71, and where to find it ?


You should try http://www.ebar.dtu.dk/~c888600/newpic.htm it programs all
the PICs you ask for and more. It has its own software for 16x84 and 12c5xx
and a driver for PIP02 software for the other mid-range PICs
It is powered from the serial port and is very low cost.
Read the pages and follow the links to understand what all this means.

Mo