allegro to pads conversion
There is no direct way to do the conversion from Allegro to Pads. Mentor does not offer a translator for that conversion, and Cadence does not export to a compatible format.
It is possible to import Allegro files into the newest version of Altium Designer. Mentor does offer a translator that can go from Altium Designer to Pads. So, one method would be to import the Allegro design to Altium Designer Summer 08 version, save it, then translate that into Pads format. The Altium importer is outstanding, so the result should be pretty good.
Another way is to use Mentor's CAMCAD translator. It has never produced good results for me, but it does work.
Still another method is to install Valor's ODB++ addon for Allegro, save an ODB++ version of the Allegro file, load it into CAM350, and then save a PADS file. It does a passable job, but not as good as using Altium Designer.
If you would like for me to try and convert your board for you, drop me a PM with the board file attached as a zip or rar. I'll see what I can do.