Joomla! and VirtueMart are both designed for easy use in a PHP / MySQL environment. All you need is to download the latest Joomla distributio and install the VirtueMart package on top of it. Joomla provides the Core System and the Framework, which VirtueMart can use. So you end up with a complete Shopping Cart Solution within your own dynamic Website, together with many other Plug-Ins, Components and Modules, like Forums, FAQ, Guestbooks, Galleries. etc.