<preach>As is normal practice with any computing device, you should be backing up your important data anyway </preach>.
If you want to do this you should read the Project Wiki, to find out what it does, and how to do it.
However, personally, the stuff I have on my Archos devices (photos, music, videos, etc) are all copies anyway - the masters are all kept on a laptop, and I back THAT up to a separate hard disk drive. So anything on my device is consumable. After doing anything important on the device, I just copy back everything en masse, and update any libraries as appropriate. By doing this, you're not strangled when it comes to doing anything of importance to the device.
In addition to this, with particular reference to the device, I use the app "Android Manager Free", free from Appslib, to backup all my apps to .apk files, which I then store on my PC, by simply copying them over via USB cable. That way, I can re-install them easily by copying the .apk files back onto the device, and installing them from there. This is all normal file management / good housekeeping, and keeps you in control of your device.
This latest version of UrukDroid is excellent in terms of performance, and functionality. Archos could adopt it "as is" for their next firmware release. It really brings out the best of the Gen 8 devices.
Just read and follow the instructions carefully. My recommendation is, when it comes to the bit where you are offered "Easy method" or "Advanced method", choose Advanced, then accept the default partition size options.
One thing to note. Google has finally got their act together with the Market. They now offer the option to rent movies (films for other UK readers, like me
Now that this is finally in operation, we can see the effect of the warning that Archos has been issuing for years. To root your device, you need to install the SDE, which Archos provide on their website. Going back as far as the A5IT, Archos has been warning people intending to install the SDE, that doing this will prevent DRM management. So, with a device rooted by installing the SDE, you will not be able to rent Movies. Google detects that "your device appears to be rooted", and will advise you to watch any rented movies on your PC, or apply to them for a refund.
It's taken about 3 years for the relevance of this Archos warning to become apparent. But, if you don't intend to rent Google movies to watch on your device, then it's no problem.