the first option.
Extensions are installed on a per user basis.
The installation of eCart 4 into the new user will not conflict with the eCart 5 installation under the other users account.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.