Torben, I haven't used the current ecommerce setup either, but have hacked much on the original port. What are the issues you are having a problem with? Are there features missing which your boss expects? Or does it just not install?
Ecommerce itself is a very broad area. This module is good for a retail shop, but the backend is more important than the sucky front end, as you can easily create a new frontend. You should also note that every retailer has an infinite desire to customize their site with features, so you constantly have to hack in these features. So even if the package (OpenACS Ecommerce or other) you choose does everything you want when you install it, soon you will discover it's weaknesses.
