I have connected my standalone DVD player to my computer as well. Video In or Video Out should not matter on your graphics card. I am not sure if you will have the same sort of setup as I do, but this is what works for me.
. You will need to connect the S-Video cable from the Video Out on the DVD player to the S-Video port on your graphics card.
. You'll need audio too. You might need a Y-Splitter in this case. I got one from Radio Shack. Connect the Audio Out from the DVD player to the Audio In on your PC/Graphics Card.
If you are trying to copy the contents of your DVD to make a backup, like Chriso said, it would be easier to get a DVD drive for your PC and get a ripper. Not only is this easier, but copying the DVD this way is, in my opinion, a hell of a lot less time-consuming.
If you're planning on copying the DVD by way of a standalone, you'll have to watch the DVD in realtime. Connecting the standalone to your PC will not show up as an extra drive and allow you to access the DVD files.