Burning with dvd soft?

I have dvd soft on my pc. When i burn movies that i have copied from a dvd to my pc then converted it to .avi files, i play them on my dvd player and it comes up with unrecognised files, yet when i download .avi files and burn them to disk with dvd soft it plays on my dvd player with no problems at all. Anyone else had this problem? and how did you overcome it??