Simple Aspect Ratio Question...LOL

Well, I got the software, loaded up four .avi files and set to automatic did the conversion.Took DVD to DVD player, inserted it into the player with much anticipation, wanting to see Starbuck in living color, and with much horror to find that she had been stretched out to fill the screen to look like the rest of those anorexic waifs on TV rather that my Rubenesque Starbuck!!!
ARGGGGGGGGH! It must be the Cylons.
There are many copies but mine screwed up.

OK seriously now. Why the stretch? Are Battlestar Galactica rips in a letter box form?
Should I have used 16:9 instead?
And no, changing the settings on the DVD player did NADA! All the settings (16:9, 4:3 letterbox, 4:3 pan scan) looked identical.
Any help appreciated.
I don’t want any more useless coasters.
How do I know beforehand how to force the issue if I know the resolution of the input?
I thought most .avi TV rips were pretty much the same resolution and aspect.
Correct me if I am wrong.
This process should be idiot proof.