I often find myself interfacing PIC based projects to some program running in a Win32 environment. The serial port is a convenient interface to use in these cases. For debugging serial data communications issues I recommend RealTerm which is available at SourceForge. The MSDN Technical Article "Serial Communications in Win32" is a good source for details on event driven Win32 serial communications programming. See www.beyondlogic.org for good documentation on PC ports, including the serial port. The Win32 source serial.cpp and serial.h are a small serial data comm library which should be easy to understand. The library is non-event driven and has no handshaking support. I've included a small test program serial_pic.cpp which is a Win32 console application to test the library by sending a file over the serial port.
This is a simple project to send data to and receive data from a PIC MCU.