[Plugin: WP e-commerce] Protecting downloadables folder?

I’m using the latest WP e-commerce plug and wondering about protecting the downloadables folder in cpanel.. I could be wrong, but it seems that if someone figures out the correct address they can access the files without purchase?

I’m wondering if adding a blank index.html file to the downloadables folder will protect/hide the product files from people trying to access directly? Will adding this index.html file cause any issues for people who purchase/checkout and then go to download?

Or is there another/better way to protect these dowloadable files?

Thanks for any help and suggestions!