Just in case anyone is interested, I'm working on adding code to the SAD batch file to delete the folders not needed for certain OS types. As an example, if you're running SAD2 on a Vista OS, then this is what would happen:
1) extract drivers to the system drive
2) delete the folders not needed (Server & Win7 folders) so all that remains is the \All & \Vista folders (or folders from older packs).
3) dpinst is executed.
This should speed things up since dpinst wouldn't have to scan irrelevant driver folders. It would also be optional, just like the new KTD option.
Since I don't have server 2008 installed, I don't know what the registry keys are that identify it. I'll have to install server 2k8 in a VM just to look at the registry.
*Edit
Got it.
FOR /F "tokens=2*" %%A IN ('REG QUERY "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v InstallationType') DO SET installtype=%%B
Responses would be either "client" or "server". Easy.