The good news is that Microsoft and others started working on implementing IPv6 quite some time ago. Windows 2000 saw an IPv6 Technology Preview program that was also limited in capability and is no longer supported. This Info World article offers tips and advice for Windows admins.
“The day has finally arrived — IPv4 addresses have run out. When the Internet Assigned Numbers Authority (IANA) started handing out IP addresses, they had about 4.3 billion to disperse. Sounds like a lot, right? But when you consider there are 7 billion humans on the planet, with people in developed nations needing two or more devices with an address each, you can see how this number might become depleted.”