Check out this guide:
How to convert DVDs back to MPG files for reauthor or reedit - VideoHelp.com
The advantage with this is that you don't have to piece together the VOB files by hand. I've used VOB2MPG many times and it's bulletproof.
VideoHelp.com has a lot of good information on stuff like this. It's a bit more consumer oriented but it's pretty wired in.