Application Layer Gateway Service
Windows Vista Service Details
Allows 3rd party Internet connection sharing applications to be used. In XP this was required for Windows Firewall I believe, but it does not appear to need it now. If you do not use ICS, disable it, though it will not run anyway
Provides support for 3rd party protocol plug-ins for Internet Connection Sharing.
Consequences of Stopping:
None that I can see so far. Will update.
All services listed in 'Required For' will be unable to function