Thanks for all the suggestions guys and gals!
I ended up going with Handbreak. Worked a treat however does not support AVI (MP4 and MKV only). No big deal because I was really after a conversion tool that would combine all the VOB files of a DVD.
I use DVD Decrypter and DVD Shrink to backup my protected DVD's. Highly recommended and they're both free. Support for them finished about 5 years ago but they still work with most newer DVD's. There is a new type of protection though that will trick DVD Decrypter into thinking the main VOB file is massive (80GB or so) and will automatically state you don't have enough HD space to save it. To my knowledge, there is no way around this yet.