How to get a home DVD onto the computer?

For my dad's birthday, I'm going to make a video with lots of videos and pictures of my siblings and I. We have a few DVDS we made with home videotapes, and I want to put them on my computer to work with them. However, I don't want them to be imported off the DVDs ( I want to still be able to watch the DVDs). So how do I copy them so I have them on my computer and on the DVDs? Thanks for anyone who took the time to help! :)