Are you selling them individually? Or are you trying to set up a membership site? If they're individual, OsCommerce or Zencart would work (or quite a few joomla add-ons if you're using joomla). Or are you looking more for something in an affiliate program? If you're looking for an affiliate program, I would suggest either boxedart.com or templatemonster.com since they're both so popular.
I click and bit defender went nut's and said it stop trojan.agent.AXB from downloading into ie temp folder??