ON PRACTICE VOR APCH INST STUDENT CONTINUES BELOW PUB ALT BY 1000 FT.

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I WAS IN A CESSNA 172-P ON AN IFR TRAINING FLT. AT THE BEGINNING OF THE FLT; MY CFII INTRODUCED ME TO DME ARCS. THIS WAS MY FIRST FLT IN A CESSNA 172 SINCE MAR/94. I USUALLY FLY AN AMERICAN GENERAL TIGER. THOUGH I HAVE NOT EXPERIENCED VERTIGO IN THE TIGER SINCE MY INITIAL INTRODUCTION TO INST TRAINING; I EXPERIENCED IT TWICE DURING THE FLT IN THE CESSNA 172. THE TERMINAL FORECAST FOR PHILADELPHIA NE (PNE) ARPT FOR XA00 ZULU (XB00 AM LCL) WAS 5000 SCATTERED; 25000 SCATTERED; SURFACE WINDS OUT OF 210 DEGS AT 10 KTS; VISIBILITY GREATER THAN 7 MI WITH AN OCCASIONAL VISIBILITY OF 5 MI IN HAZE. FOR THE MOST PART ACTUAL CONDITIONS MATCHED THE FORECAST. WE WERE DOING THE VOR INST APCH TO DOYLESTOWN (N88) USING THE 240 DEG RADIAL FROM THE SOLBERG (SBJ) VOR. I DID NOT SLOW TO APCH SPD AND DSND TO 2000 FT MSL UNTIL I WAS NEARLY AT GROOM INTXN (340 DEG RADIAL FROM THE YARDLEY (ARD) VOR. AFTER SOME PROMPTING FROM MY CFII; I SLOWED AND DSNDED. WE WERE ABOUT 2 MI OUT FROM DOYLESTOWN WHEN MY CFII ASKED ME IF I WANTED TO PULL UP OR CONTINUE TO FLY INTO THE GND. AT MY CFII'S COMMENT; I IMMEDIATELY APPLIED FULL PWR AND CLBED TO 1020 FT WHICH IS THE MINIMUM DSCNT ALT (MDA) FOR THAT APCH. SHORTLY THEREAFTER; MY CFII TOLD ME TO REMOVE MY FOGGLES. I MISREAD THE ALTIMETER; THINKING IT WAS 1600 FT MSL WHEN IT WAS REALLY 600 FT MSL. THE TERRAIN ELEVATION IN THAT AREA IS APPROX 400 FT MSL; SO WE WERE ONLY ABOUT 200 FT AGL. WHILE THE AREA IS NOT DENSELY POPULATED; THERE ARE RESIDENCES IN THE AREA AND I COULD HAVE COME WITHIN 500 FT OF THEM. HOWEVER; I AM NOT COMPLETELY CERTAIN OF THIS SINCE I WAS STILL UNDER THE HOOD. MY CFII AND I DISCUSSED MY MISTAKE DURING POST FLT. THIS IS THE FIRST TIME I HAVE EVER MISREAD AN ALTIMETER. I THINK THE FOLLOWING FACTORS CONTRIBUTED TO IT: INSTANCES OF VERTIGO EARLIER IN THE FLT; UNFAMILIARITY WITH THE CESSNA COCKPIT RELATIVE TO THE TIGER; GETTING BEHIND THE AIRPLANE BY NOT DSNDING AND SLOWING PRIOR TO GROOM INTXN; AND POOR INST SCAN DURING THE FINAL PHASES OF THE APCH.