I need a good program for converting VOB files to AVI files

If those .VOB files are on your computer, this video converter can convert them to .AVI.

If they are on DVD disc, you need this DVD Ripper software.

Hey, pal. If you are using a Mac, I think iSkysoft iMedia Converter for Mac would be the best choice, which can convert DVD and Video both to iPod (also to Quicktime, iMovie, iPhone...).
It was recommended by lots of famous mac-related sites, such as macworld.com, macnn.com, maclife.com, etc. You will never know how powerful it is. It’s the best all-in-one Mac converter I have used ever.
Glad to share.
And you can find the truth on iSkysoft official website:

http://www.iskysoft.com/imedia-converter-mac.html?page=126

i am using iskysoft video converter(for windows).
so far so good.

I suggest that you use E.M. HD Video Converter ,

It can :
" Converting all videos to HD Video
Convert video and AVCHD to DVD, DivX DVD
Create Blu-ray Folder for PS3 and Blu-ray Player "

Link : http://www.google.com/search?hl=en&q=E.M.+HD+Video+Converter&btnG=Google+Search&aq=o&oq=

Hope this software is you want !

Hey! I had a good luck with this DVD Converter Software</a> which helps me convert vob files to AVI. I find it from this guy’s blog - http://www.mydigitallife.info/2009/11/24/wondershare-dvd-converter-ultimate-all-in-one-dvd-video-tool-review. It is for windows. I think you can have a free try of it. Hope that helps.