#1 Typos and options
Scan tab has radio button for "RCP Scan". I believe this
should be a check box on the Options tab, as the "RPC
Scan" can accompany other scans.
Scan tab entry for "Idle Scan Host" should read "Idle
Scan Zombie" or something similar, so as not to
confuse against the target host.
Lastly, as NMapWin is really a tool to assist in creating
the proper command line, it might help to have a
checkable menu item that would "open up" the created
command line to manual editing before launching the
scan. This would allow the interface to be used with
newer releases of NMap by replacing the executable in
the /bin directory and adding any "new" command
options manually.
Just some thoughts!