AnyDVD will remove the copy protection, DVD decrypter will do the same but has to copy the files to the HD. From there on, you can convert with one of the many DVD --> AVI conversion proggies. Look at www.divx-digest.com for all the utils you can imagine.
There are many single-click (not really) apps that will help you do this, but to make good conversions requires some skills and manual (divine) intervention. Read up and test on some smaller samples until you get the hang of it.
I've been using Nero for years and it's very fast and reliable, with great image quality (when shrinking DVD9 to DVD5). But the other way round - making DVDs out of MPGs and AVIs - is just plain BAD and slow.