How do I change this?

You tube wants you to change the format of your videos to a format the except and to resize to 320x240. I did and my quality was terrible. What is the best program to use to change the format and to resize without loosing the quality.How do I change this?
i always use DivX Converter, cuz youtube supports divx files and as u know divx format is the best one cuz takes less space , once i converted a 6gig avi file to a 20mg divx as i remember ,



so i think DivX Converter is best for what u want to do ;)



u can also resize ur video to 320x240