The files you have ripped to the hard drive should already be in a Video_TS folder if you used File Mode in DVDDecrypter. If you just have the vob, ifo and bup files, you can make a folder with the name Video_TS and put them all into it. WinDVD should be able to recognize this folder and play the movie correctly.
To burn this movie to a disk, use ImgBurn and look at this guide: http://forum.imgburn.com/index.php?showtopic=4632 ImgBurn is the updated burning engine from DVDDecrypter. By the way, this will only work if the files are small enough to fit onto a single layer blank dvd. If they are not, you will have to compress them with something like DVDShrink or burn to a dual layer disk.
I suggest doing a bit of reading on the various tools available for backing up dvds. There are guides in the Copy DVD forum, and you might want to look through this thread: