This is the program I use to encode videos so that I can watch them on the GP2X. This program can't be easier to use: it has got 3 quality presets (tested, of course), and the UI comes in both Spanish and English. Generated videos work with firmwares 1.4 and 2.0, although they hang when in "save mode" (I'm starting to think that this is just a problem of mine). A longer description of this program and its installation process is included in the README file.
This is not the invention of the century, just give it a try and tell me if you found it useful

Download Here --> http://archive.gp2x.de/cgi-bin/cfile...,0,0,0,17,1621