You want to make back-ups. Go here: http://www.videohelp.com/ &
http://forum.dvd-guides.com/ There's many a program that can do that for Windows. You need a program that deciphers the security coding on the disk, & copies it to your computer. If you have a dvd9 format burner then you can burn directly onto a dvd9 format dvd-r disk (ie: 8.5 GB) after having extracted the original to your computer. If you have a dvd-5 format burner (4.7 GB) then you'll need a 2nd utility that reduces the size down to fit onto a 4.7 GB disk. By the way that really means 4.37 GB in reality. They size dvd's in the same way they size hard disk drives. eg: A 60 GB hdd will only have about 57 GB available after formatting. Those sites above will give you multiple choices for each purpose.

If you were using a mac then I could suggest specific utilities to get a hold of.
I frequently back up movies onto dvd-rw to watch at a later time if I'm too busy to watch them immediately.