If this is in dvd-video format, and there is no advanced encryption, DVDShrink will be able to make a copy for you. If the dvd is pressed (commercially made) and is larger than 4.3gb in size, DVDShrink will compress it to fit onto a blank, single layer recordable dvd. If it is already small enough to fit, no compression will be applied.
Here is a complete guide for using the program: http://www.afterdawn.com/guides/archive/how_to_copy_dvd_with_dvd_shrink.cfm
Once you have a copy on the hard drive, you can use ImgBurn to burn to a disc.
If there is absolutely no copy protection on the original disc, and it is already small enough to fit onto a single layer dvd, then the whole thing becomes much easier. You can use ImgBurn to make an ISO file of the original disc, then burn the ISO to a new disc.
Here are the instructions on how to copy the disc to an ISO: http://forum.imgburn.com/index.php?showtopic=6379
And the instructions on burning an ISO: http://forum.imgburn.com/index.php?showtopic=61