Thanks for Minion and gvisser I was finally able to convert several VOB files into avi and wav. As Minion suggested I used DVD2AVI and VFAPI. Took many attempts and I tried different versions. Ended up with DVD2AVI 1.82 OGO and VFAPI 1.04b (NOT used as a Plugin for DVD2AVI). In general it works fine now but I have 2 clips where DVD2AVI doesn't create audio files. I have no clue why this is the case. It is Dolby Digital sound. The conversion worked fine with other clips that have Dolby Digital. I tried to select different audio tracks and several audio settings but nothing helped. The sound is there, I can hear it when I play the VOB file with Media Player. When I look at the statistics tab it says "Audio Format: UNKNOWN". Any suggestions what that might cause? I'm clueless...
PS: I've found one hint. It also says DTS digital sound. May that be the problem? Does DVD2 AVI have problems with DTS?
Ah, forget it. I tried it again and again and I seemed to have chosen the wrong audio tracks. Now it worked... *blush*