Drupal 5.x or 6.x - Which is best for E-Commerce?

Hi all,

I'm working on a website for medium size organization. Its a simple site with information on the organization and their products. We are also planning to use some ecommerce module to sell products online.

Please help me chose the Drupal Version - 5.x or 6.x - for my requirement.

Also, please comment on which module to use for selling products, UberCart or ECommerce?

Thanks in advance,