What are you trying to copy? If it's not commercial movies i.e. copy-protected, you can just use Nero Burning ROM's DVD Copy. Set your source drive to one of the DVD drives and your destination (along the top bar, once you've gone through the wizard) to the other, and click BURN. This will work for data discs as well as Video DVDs.
If you're trying to back up your personally-owned commercial movies, check out the Ripit4me and IMGBurn tutorials floating around the forums or possibly under Guides. There are some tools e.g. DVD Decrypter and DVDShrink which Ripit4me depends upon to work but it'll beat anything.
FYI, it's best to have your newest, and preferably double-layer-capable drive, as your destination drive and your older or non-DL drive, if you have one, as your source. This gives you more options and usually better media compatibility.
-Do you believe you own your computer and shouldn't be told what you can run and do? Then say *NO* to Microsoft Vista!
-Since half the questions here involve media problems, here ya go: Only use Verbatim or Taiyo-Yuden discs (get your TYs from Rima.com, not Supermediastore or meritline). Forget the rest, no matter what "brand" they sell under. Always burn at 4x speed regardless of the speed rating of this discs or your drive. If you have burn problems with these then you have to update your drive's firmware. For double-layer discs, only use Verbatim DVD+R DL and burn them at 2.4x speed.
