Sorry for digging up an old post but I found this during searching for the exact same thing. I'm looking to do the same but I cannot find any information anywhere about how to do it, just information that you CAN do it. WSUS 3.0 even has the option to download Dynamic Updates for Vista in the packages, but even search for help with WSUS doesn't come up with anything. Frustrating to say the least. I've had a look a the <DynamicUpdate> function in the unattend.xml, and there are only two options available. One being the one you posted to enable it, the other being WillShowUI, which apparently "specifies in what circumstances to display the user interface for dynamic updates". Not exactly sure what that means and I haven't had the chance to try. Can anyone shed any light on how to this? Would be very much appreciated.