Online ordering should be easy

Mary, I'm totally with you about online ordering. So many companies just don't get it. Worse yet, utility companies in Australia are just appalling. Origin Energy, I'm looking at you, dickheads! Their online "order" form seemingly goes absolutely nowhere. How useful!

So on that note, I've been thinking of setting up an online ordering site myself. More as an experiment in marketing and conversion rate improvement than anything else. If I decide the tax crap isn't going to make it onerous, I'll be doing it shortly.

What software should I use? This will be a single-product site, but I'd like to have proper order management and notification, along with rudimentary stock control ideally. Online payment is essential. And I want to run it all (except perhaps the payment) on my own server. Not written in PHP would be good.