Possible to root Archos 79 Platinum
YES! It is possible to root the Archos 79 Platinum using the following methods:

VROOT-root exe file for use on Windows machines

And to replace the superuser-app with an English version:

English Superuser and busybox etc

Yoy may also first want to check out the following link to make sure USB works properly (also google on how to enable developer-mode and USB-debugging on Android devices in general):

Enable Archos USB devices

I just rooted my device, so I know for sure that it works.