What version of vmware are you trying to use?
edit: VMWare workstation and Server both should be able to open the .vmx file using a file open/import and pointing it to the vmx file (which should, hopefully, point correctly to the vmdk file - otherwise, you can hack the .vmx file yourself to point to the correct path).
Importing the vmdk into an VI3/ESX server will require a little more work, but the easiest way to manage it would be to use the VMWare Converter.