Open source shopping cart webapp for subscription payments?

[Scott Garman]

I'm wondering if anyone on this list has experience with open source
ecommmerce shopping cart applications, such as Zen Cart?

I'm looking for something to manage recurring subscription service
billing (monthly), and which has support for Authorize.net (mandatory)
and PayPal (strongly desired).

Thanks,

Scott

-- 
Scott Garman
sgarman at zenlinux dot com