First we need a program to turn the DVD into an "ISO" file. A snazzy program called DVDShrink can be downloaded here. So that's step one. You can show appreciation of this program by donating to the makers of it here.
Now that you've got DVDShrink installed, pop your DVD in your drive, start your new program and click "Open Disc." After its finished opening, click "backup" and make sure "ISO Image File" is selected in the first box, and select your target image file (destination folder and filename) where you want to the file to go. Click OK! It's working...
While that's working, you can minimize it and download InfraRecorder. Install the program. If it's not finished already, wait for the DVDShrink program to finished working, then close it to get it out of the way. Run InfraRecorder, click "Actions" at the top, click "burn image" find the file ending in ".ISO" you just made in the previous step, then click ok! You're done!
After it's finished burning, just test it out in your DVD player. If your DVD player is as crappy as mine, you'll appreciate when after breathing on your disc the wrong way, you have a backup thats smudge less. I really think they make those movies cheap on purpose, because my CDs used to be scratched RIDICULOUSLY, and they would still work fine. The new technology gets a fingerprint and goes haywire. Also, if you're like me and have kids (or animals for that matter), you'll appreciate when your kid, dog, monkey, evil brother, etc. tears your favorite movie up that you've only watch 107 times - A pity.
Disclaimer: You should ONLY back up DVDs you have a legal right to do so with. If you are illegally copying DVD's, you should pick up the phone now and dial 911, tell them there's a crazed DVD copier on the loose and you know where he/she is. In all seriousness STILL, if you really like movies, you should be contributing to their production by paying part of the costs(buying them)... I know they make hundreds of millions, but some of those movies cost hundreds of millions to make- sometimes they loose a lot of that. What the hell would we have done without the final creation of the Star Wars Prequals? I'm being serious, DON'T MESS WITH STAR WARS! I WLLL BRING OUT MY LIGHT SABER! I WILL CHARGE MY BLASTER! May the force be with you.