QUOTE (cluberti @ Sep 11 2008, 11:44 PM)

If you have two scopes on the same network segment, there's no real way to segment the assignment short of using reservations. However, if you have two separate network segments used by these two scopes, you could put the DHCP server on it's own segment and use DHCP forwarders to do the job.
However, if the DHCP server is on the same network segment as the machines you wish to segment, you will have to use DHCP reservations. The DHCP DORA process is UDP broadcast, and there's not really any way to keep certain machines on a certain scope in this configuration without MAC reservations.
There are alternative processes, such as DHCP helpers. This type of function, I don't think, is included with Windows, but network management software (such as Altiris) can manage it. Say computers with "insert-variable-here" will receive IPs in this scope, and computers with "other-variable" will receive IPs from another scope. The variables could be DMI information (from the BIOS), computer name (trimmed) or any other bit of information that the computer can transmit. Or in an extreme case, use one scope for preliminary info and when the server determines what type of interface it is, will reassign an IP from one of the two other scopes.
But perhaps a real question is, if both of these types of interfaces are on the same physical network, what is the true purpose of assigning them to different IP ranges?