Won't work. If you have Apple's MPEG2 component, you can open the VOB files directly, but as usual, no sound. (And no de-interlacing, which can make things messy.)
So far, I've found no support for opening up DVDs (that I own, before anybody bitches) that I've copied to my drive. I'd love to see the option, because it would make Front More much more useful, but I really don't expect to see the option coming from Apple. That's the problem with Apple making this - they aren't going to toss in everything, being a big company, that just a bunch of guys making the program would.