Over at MCPmag.com, I pen some great info on how to deal with IPv6 when you haven't yet implemented it in your network. There, I talk about the new "-4" switch used with ping to ensure that you're getting a IPv4 response as well as the registry key you can set to disable it completely on your Server 2008 & Vista computers.

...there are two things you can do that can assist with keeping IPv6 out of the picture for now, at least until global warming speeds IPv6's glacial melt-off. The first is the "-4" switch used with the ping command. IPv6 responses to ping requests can be confusing, so this switch forces ping to use IPv4 for the query. To use this switch, simply enter it before the hostname you want to ping, as in:

ping -4 {hostname}

Another option is to disable IPv6 functionality entirely. This can be done by editing the registry. In the location HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\ create a registry DWORD value titled DisabledComponents. Set the data for this value to FF in hex to disable all IPv6 components except for the IPv6 loopback interface. This setting also configures the computer to prefer IPv4 over IPv6. Restart the computer for the setting to take effect.

Later on, when you implement IPv6 in your network, simply reset this value's data to 0 and reboot again and you're merrily on your way to the networking of tomorrow.