You can use DVD Flick as mentioned by other users. Basically your DVD-Video discs will contain folders called VIDEO_TS, for the video files, and AUDIO_TS, which will usually be empty. What these programs will do is convert your videos to the (.VOB) format with (.BUP) and (.IFO) files all inside a VIDEO_TS folder.
When you create DVDs, it will reduce the quality of your movies (because you're converting one lossy movie format to another lossy format) and increase the file size. You may get one or two hours of movies on a DVD instead of the six or seven hours you would get using AVI and a better codec.
Once you have the files inside the VIDEO_TS folder all you have to do is burn the VIDEO_TS folder onto a data dvd disc.
See How to burn DVD folders with ImgBurn for a walk-through. How to burn a DVD Folder with ImgBurn - AfterDawn: Guides
However, ImgBurn is included in DVD Flick and AVStoDVD .
Alternatively, Windows DVD Maker, which is included in Windows 7 , will do the job too .