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!