Is there something special that I need to do because I'm joining a physical machine to a virtual domain?
Nope, nothing special needs to be done.
You should check to make sure that your vista installation can ping your domain controller by IP and by Name first. Perhaps your Vista machine is configured with a different DNS server then the rest of your (virtual) machines on your 2003 domain?
I am also wondering if your virtual machines were set up behind a NAT network (which might be the default network configuration if you used the VMware New Virtual Machine Wizard when installing them).