I personally wouldn't use AutoGK for this. VirtualDubMod is probably the easiest to get to grips with. You'll need a lossless codec (e.g. Lagarith) as well.
Load the VOB into VirtualDubMod, go to Video->Compression, select Lagarith, and configure it to use YV12 colorspace. Select Audio->none (as you will be loading your demuxed/decoded audio separately). Then save as AVI. Do not change any other options; the output AVI will be exactly the same quality as the original DVD.