After install AlfrescoEnterprise-2.1.0-Setup.exe (about 60M), then login with Admin or any other user account. In Data dictionary, there is no Web form item in the list. But with build I download, it said "Combined package, also with Web Content Management".
Yes, WCM needs to be installed as an extension (e.g. run AlfrescoWCMEnterprise-2.1.0-Setup.exe or unzip/untar the equivalent package).
Alternatively, the Enterprise Trial (http://www.alfresco.com/products/ecm/enttrial/) has the option to download and untar a combined bundle (alfresco-enterprise-combined-2.1.0.tar.gz).