How to convert DVD to AVI or MPEG

I have seen people having DVD ripped movies on their hard disks in AVI format of only 800,900 MB sizes.
Can someone help me please, how can I do it? or how can I convert to MPEG format?
Please someone help.

Try DVDX at this link . I’ve used it once & it seemed to work OK.

will it also convert avi to dvd format