Thoggen is a simple dvd ripper that's very easy to use. It has less features than some of the more advanced dvd rippers but it doesn't require as much setting up etc. I've also read good revues about Acidrip, although I've never used it myself.
vlc should also be able to rip dvds, but I've never managed to get it to work for me. (although it plays dvd's well.)
you can check with Synaptic package manager to see what is installed on your system. It's a good idea to write down what dependencies a package pulls in when you install something if you are experimenting.
Also, if you run
sudo apt-get autoremove
from the command line, this should remove some latent packages that are no longer needed. (dependencies for packages that have since been removed.)