which is the best all around ecommerce package?

hi gang

my boss has asked me to look into which ecommerce package we should consider
using. this is a new area for us, so i'm feeling lost. we're primarily asp
developers, have lots of ms access and ms sql experience. we're looking for
something that has sales tax calculations, non-session based shopping cart,
delivery fee calculations, multiple currencies support, store management
features. is there anything else we should be looking for?

what are the standard fees associated with ecommerce aside from the purchase
of the package?

there seem to be tons of free and license based options on the web - too
many to make a clear choice. i'd appreciate it if anybody has a sense of
what the more popular packages and why. anybody have a strong pref for one
package over another and why?

what would you guys recommend?

tks