it depends on the play length.
to do so, dvd rip each of the movies into a hight quality avi format, or u can just simply copy the files into your computer.
Using nero express you will simp,y drag and drop these movies into the list you wana burn. It simply works. But remember that there is always a limit that you can not cross. 6 movies doesn't sound logical unless they are short.
My way is to keep them in avi format and watch them using the computer. I might connect it to my HDTV and it gives a better quality than DVD it self.