What is your reason for wanting a VMware certification? If you are a View administrator or wish to work as one, VCA4-DT is of benefit. If you want to work more widely with virtualisation, with vSphere for example you might want to consider VCP5 instead, that will also qualify you for the VCP5-DT when it is released shortly.
See http://www.vmware.com/certification for links to all current VMware certification programs
Scott.