What are you trying to undo? Assign new static IPs? Assign static IPs in general?
Are you having one computer act as a server (assuming the NAS)? If that was switched to 7 awhile ago, you should be good.
Windows 7 has "normal" networking and groups or whatever they call it. If you have all Win 7 machines, setting up the group is basically the same as mapping to a network drive.
Did I misread the question?