PC World has a detailed tutorial onhow to install a DVD drive and transfer videotape to DVD. The main reason why you'd want do do this? "Create DVDs from videotape, make large-scale data backups, use as a 4.7GB drag-and-drop drive."
It doesn't appear to be too complicated and the majority of the costs lie in the DVD burner itself.
Step-By-Step: Burn Your Own DVDs for Backup or Video Playback [PC World]