Trying to ipconfig /release and /renew on Windows Vista is a bit of a pain in the hind when you want to do it from Command Prompt. You need to find the command prompt, right click and run as admin, accept UAC. Brad Bird mentioned in our Vista Enterprise class on Monday and was also in the Vista training kit that if you hold ctrl and shift when you press enter, it will run the command elevated, press Alt-C to continue and its up and going. For example, type CMD in the run box, press ctrl-shift and enter; press Alt-C to accept UAC and now you can release and renew away and its as just about as easy as it was under XP.
Todd's Tips for System Adminstrators