DVD disk is a quite fragile medium and even despite special protection layer on each disk it is still very easy to damage.
Unlike VHS tapes, even dropping the disk or putting it in its box in the wrong way sometime might be enough to scratch it and get reading errors as a result. Taking in account that some collectors- or limited-edition DVDs can cost a fortune, it does make sense to make a backup copy and prevent the loss of the favorite disks. All that it takes is a PC, DVD-Recorder drive and special software.
There are many ways to backup DVDs and the choice between them depend entirely on users preferences. If you have a good home cinema and prefer to have best available quality, backup copies are best to be made on DVD disks. It is rather easy to do if the original disk is single-layered (DVD-5), but in case of double-layered (DVD-9) disks it becomes much more difficult; and unfortunately, most movies are recorded on such disks.
It might seem that double-layered recordable disks (DVD+R DL & DVD-R DL) are the best solution for this problem. However, this solution is not available to everyone as double layered disks require special DVD-Recorder drive that can handle them, and these drives are not too common yet.
Fortunately, special software (such as free DVD Decrypter and DVD Shrink combo or commercial CloneDVD utility) allows copying double-layered DVD on two single layered disks. And if shuffling disks in DVD player is not an option, it is possible to squeeze double-layered disk on one single-layered DVD. Of course, this would involve some reduction of image quality and stripping of bonus materials, but such reduction will hardly be noticeable on most TVs. And most bonus materials are useless anyway.
You don't want to cram DVD backups on your shelves? In this case it is possible to save all DVD backups on your hard drive by using exactly same programs. The only requirement here is the size of the hard drive; obviously, it should be big enough to store all data. In this case, should anything happen with original DVD, it will always be possible to restore it from hard drive.
But what if you don't have any home cinema and you prefer to watch movies on PC? In this case you won't actually have to record anything, as it is possible to watch movies from DVD backups on your hard drive at any time (this will require DVD player software, such as PowerDVD or WinDVD). If your hard drive is not too big, it would make sense to repackage movies from MPEG-2 (which is a standard for DVD video) to some format with more advanced compression such as MPEG-4 (AVI, DivX, Xvid, Mpeg-4). All that it takes is special ripper software, such as BitRipper, AutoGordianKnot, SmartRipper and others. As a result of such conversion the movie can be shrinked to fit standard CD, which is 5 times less than the original. And by using smart compression techniques it is possible to keep video quality pretty close to the original one.
However, after recording DivXMpeg-4 movie on CD or DVD in most cases it will be possible to watch it on PC only, as MPEG-4 capable DVD players are not too common. Of course, there are certain programs that can convert Mpeg-4 back to DVD, but such double conversion is highly unlikely to improve quality. Apart from that, most users usually strip multi-channel sound during DVD -> Mpeg-4 conversion and keep only stereo. As a result, watching DivXMpeg-4 encoded movie on the home cinema doesn't make much sense and won't be particularly satisfying too, especially if the movie is rich in sound effects. Mpeg-4, however, will suit old classical movies best, since they usually have mono or stereo sound initially; and classics remain classics regardless of quality.
Summary
It should be quite easy for you now to choose most appropriate backup method. If you prefer maximum quality available, full DVD backup on one double-layered or two single layered disks is your choice. If you still prefer quality and have a home cinema, but can sacrifice a little of image - backing up DVD on one single-layered disk will suit you well.
And if you prefer to keep and watch movies on your PC, same backup programs that you use DVD backup will allow you to create a copy of DVD on your hard drive. In case if your hard drive is not big enough to store full DVDs and you don't have anything that resembles home movie theatre, the most sensible thing would be to convert DVD to Mpeg-4 format.
Artem Chlegov is a editor and writer for DVDSoftwareGuide.com - a DVD software review website.