THE PLT RECEIVED 2 WX BRIEFINGS BEFORE TAKEOFF & WAS PROVIDED FLT PRECAUTIONS OF IMC TO CONTINUE BEYOND 0900 EST. ALSO, HE WAS ADVISED THAT THE MOUNTAINS WOULD BE OCCASIONALLY OBSCURED & ICING COULD BE EXPECTED TO THE WEST BELOW 6000 FT. DURING BOTH BRIEFINGS, HE REPORTED HIS INTENTIONS TO FLY UNDER IFR; HOWEVER, HE DID NOT FILE A FLT PLAN. AFTER HIS LAST BRIEFING, HE SAID HE WOULD CALL BACK AFTER REVIEWING HIS CHARTS. BEFORE TAKING OFF, THE PLT ADVISED GROUND CONTROL HE PLANNED TO CRUISE 'JUST AROUND 1100, RIGHT UNDER THE DECK.' HE TOOK OFF AT APRX 0845. AT 0853, RADAR SERVICE WAS TERMINATED, 9 MI EAST OF THE ARPT & NO FURTHER CONTACT WAS MADE. SUBSEQUENTLY, THE ACFT CRASHED ABOUT 75 FT BELOW THE SUMMIT OF WHITE OAK MOUNTAIN, ABOUT 10 MI NE OF THE ARPT. AN EXAM REVEALED THE ACFT MAD IMPACTED IN AN APPARENT NOSE LEVEL, RIGHT WING LOW ATTITUDE. NO PREIMPACT, MECHANICAL PROBLEMS WERE EVIDENT. LOCAL RESIDENTS REPORTED LOW CLOUDS WHICH OBSCURED THE HILL TOPS.