If you need a shopping cart with CRM you could create a Joomla portal and install Virtuemart. Then you can enable SEF in the Joomla configuration and download Joom SEF which uses mod_rewrite to rewrite the URLs to be human and search engine friendly. Also has adavnced user management for newsletters and the ability to notify users concerning their purchases automatically. The only down side is that it is a quit difficult hack to bring in custom fields, and I have been using OSCommerce for this reason. You can also install an OSCommerce bridge for Joomla but it isn't search engine friendly, so I would still recommend Virtuemart as a Joomla component.
