This is the way to do it on XP, but is it possible on Windows Vista and Above?
If so how do you detect it? Is there a registry setting for it, or is there com dll or api for it?
The same registry key should work on both Windows XP as well as Windows Vista/7. This document lists it as a valid key. You may need to create it in order to use it.
You should be able to verify its state using the
Look for the IP Routing Enabled under Windows IP Configuration