Hi Tom,
I'd have to suggest
Shopping Cart Software by Volusion Ecommerce Solutions
They have very simple interface and someone who knows little html can really do a fair amount of designing and editing on their templates. That said there is also the ability for someone who is much more experienced to get in there and do some serious editing. The current version 4 is pretty good, but the soon to be released version 5 looks Really good. according to what I have read they are adding many useful features to there service which is already quite impressive. Volusion has pretty fair pricing plans and works with all of the major gateways so accepting credit cards is quite easy. As someone stated earlier Google Checkout is also a great gateway to use for accepting payments and is also supported by Volusion. I've also found that their customer support is excellent (and located in the USA! Now there's a 1st).
I would say that I have a moderate level of competence when it comes to HTML and I am very happy with the site I was able to create. If you would like to look at what I've done you can check us out at
Fragrance Stop - Designer Fragrance and Cosmetics at great Discount Prices!
Feel free to drop me a note if you want some more info.
Regards,
Glenn