A CESSNA 172 COLLIDED WITH MOUNTAINOUS TERRAIN DURING NIGHT VFR FLT. THE PLT WAS NON-INSTRUMENT RATED AND WAS VFR ON TOP OF A 1,500 FT CEILING ABOVE HIS DEST. THE PLT WAS IN RADIO AND RADAR CONTACT WITH THE LOCAL TRACON. THE PLT DID NOT REQUEST ASSISTANCE FROM THE TRACON TO AVOID THE WX CONDITIONS. INSTEAD THE PLT ELECTED TO FIND A HOLE IN THE OVERCAST. THE TRACON ISSUED A WARNING TO THE PLT OF HIGH TERRAIN. THE PLT ELECTED TO CONTINUE FLIGHT BELOW THE MINIMUM VECTORING ALTITUDE UNDER HIS OWN NAVIGATION AND REPORTED THAT HE HAD GND CONTACT. THE TRACON THEN INFORMED THE PLT OF HIS LOCATION RELATIVE TO THE APRT AND INFORMED HIM HE WAS HEADING TOWARDS THE HIGH TERRAIN. HIS ALT READOUT WAS ABOUT 2,600 FT MSL. THE PLT THEN REQUESTED A VECTOR TO THE APRT. THE TRACON INFORMED THE PLT OF A WESTBOUND HEADING TO THE APRT. THE PLT TURNED TO THE HEADING AND THEN REVERSE COURSE AND HEADED EAST TOWARDS EVEN HIGHER TERRAIN. RADAR AND RADIO CONTACT WAS LOST. THE AIRPLANE COLLIDED WITH THE EAST SLOPE OF A 1,868 FT RIDGE AT 1,500 LVL ON A SOUTHERLY HEADING.