On the wii can rip them the same way a retail ones (eg simply usb loader you use)Well it's unfortunate that there are so many games out there that I just can't but because of my financial dilemma. So when I am able to buy a game I do. Piracy isn't a first choice. The question was how do I backup burnt DVDs so I can get the ISO to play off a flash drive
Aditionally you should be able to rip them on a PC using normal disc copy utilities.
(at least iirc I used dd to do it, so most tools should work)