One freeware I've been recommending for system protection from adwares/spywares lately offers an active shield that alerts you to "any" changes about to be made in the system registry even if you are in the process of removing some program yourself. This would be the Spyware Terminator found at http://www.spywareterminator.com/
You can't completely disable the rpc in Windows. But you can easily disable the file and printer sharing service upon installing Windows and later in the control panel. That feature is enabled mainly for networking and can a system open there when used as a typical stand alone for home use.
The program above has a form of active shield that works like a firewall there and more effective then the one included in Windows. Comodo and Jetico Personal Firewall are two freeware programs that get good ratings as well. Sygate is a full retail firewall for that one.
