This video provides an demonstration of how you can create a virtual machine in VMware Workstation for Windows using an existing VMDK virtual machine disk file.
This is particularly useful if you have downloaded a virtual appliance from the VMware Solution Exchange.
For further instructions refer to VMware Knowledge Base article Creating a Workstation virtual machine using existing VMDK virtual disks (2010196).
A related blog post from our Intern Moses Masih (otherwise known as The Support Outsider), describes how he used the VMware Solution Exchange to download a pre-configured Drupal installation (and followed the instructions in VMware KB article 2010196) in order to create a vm he needed.
Enjoy the video!