Alfresco SDK (version depends on version of Alfresco you are going to use)
You could install Alfresco Bundle (http://docs.alfresco.com/4.0/index.jsp?topic=%2Fcom.alfresco.enterprise.doc%2Ftasks%2Fsimpleinstall-...). Installer will install all necessary components including database (PostgreSQL). I would recommend you to use separate Tomcat (listed above) for running Share while Alfresco itself can run on tomcat installed by installer. Having Share on different tomcat will decrease restart time.