It is not about which computer platform to use, it is about which "language" to use.
There are many ways to build a website. You can use plain old HTML. You can use a packaget (like iWeb) to build the HTML.
However, if e-commerce is a serious part of your future plan, you will need database and programming - a common approach is to use open source OSCommerce (with uses PHP and MySQL). You may also consider MSSQL + .NET.
You need to decide your business need first, then decide on the server platform (whether iWeb/.Mac, LAMP - Linux, Apache, MySQL, PHP, or Windows + IIS + .NET + MSSQL), then decide on which platform to develop on.