It could just be that, as cold as it is up there this time of year, you just need to thaw that DVD out for a bit! X-D
Those VOB files are actually in MPEG2 format - a compressed format. That means that even if you could import them into your editor, once you edit and recompress them, your quality goes straight down the tubes. Your best bet is to go back and get those original AVI files.
But I know you're not going to do that - you want to play with those VOBs, right? So let's have some fun. Copy one of the VOB files from your VIDEO_TS folder onto your harddrive, then rename the .vob part to .mpg (for instance, copy VTS_01_3.VOB to VTS_01_3.MPG). Now, you can play the file with WMP, Nero, etc., but you still can't import it into PP.
OK, now that you've had some fun, let's get back to work and get that @#$& file crammed into PP where you can edit it and hopefully preserve enough quality to make it all worthwhile -
This requires Cinematize 2 by Miraizon Software. Set your video options to "decode to QuickTime/Force Video Mode/ DV/DVCPRO/Lossless Quality"
Under even moderate usage, Cinematize will freeze up occasionally, but it's the best program I've found that can lift a/v off of DVDs and let me re-edit.