The USB to Serial converter does exactly what you want. It adds a serial port to your computer. The converter requires a driver and it should be included with the converter. After that, your serial GPS software will not even know that USB is involved. The only caveat to this is if you unplug the converter while your software is running. Depending on the driver, this may cause the serial port to completely disappear from the system. Many serial software designers don't anticipate this happening and thus it can sometimes produce unexpected results in your software (i.e. crash or hang).