Handbrake works really well, but it won't remove the copy protection on most commercial DVDs. On a Mac, all you need to do is have a copy of VLC installed, but it's more complicated on windows. I used to use AnyDVD (back when I was a windows users), it worked great but isn't free.
Maybe the situation with handbrake and vlc has gotten better now, it's been a while since I've used it on windows.