Converting video to full screen

Hi,

I'm new to the forum, so hi everyone. I didn't know where to post my problem, so I started here..
I have some videos I would like to convert to full screen, so I can watch on my Lcd tv.
At present they are in divx size 576x432, I have tried so many times now, and know matter what format I try I can't seem to get full screen. Could someone please help and set me on the right path ?

Thanks in advance for any info

kevin