WHILE ON AN IFR FLIGHT PLAN IN IMC CONDITIONS, THE PILOT WAS CLEARED FOR AN ILS APPROACH TO RUNWAY 27 AT TALLAHASSEE REGIONAL AIRPORT, TALLAHASSEE, FLORIDA. THE PILOT STATED THROUGHOUT THE APPROACH, HE HAD PREPARED HIMSELF MENTALLY TO FLY THE PUBLISHED MISSED APPROACH ABOVE THE PUBLISHED DECISSION HEIGHT. HE FURTHER STATED THE AIRPLANE WAS FLOWN BELOW THE GLIDE PATH AND TO THE RIGHT OF THE FINAL APPROACH COURSE. AT 300 FEET AGL THE PILOT LOOKED OUTSIDE THE AIRPLANE SEARCHING FOR THE RUNWAY ENVIRONMENT. HE SAW LIGHTS AND A YELLOW ROTATING BEACON AND BECAME SPATIALLY DISORIENTED AND FIXATED ON THE ROTATING BEACON. HE DID NOT INCREASE HIS SCANNING OR RETURN HIS VISION BACK INSIDE TO THE AIRPLANE'S FLIGHT INSTRUMENTS AND CRASHED. THE AIRPLANE WAS DESTROYED. THE PILOT AND ONE PASSENGER SUSTAINED SERIOUS INJURIES. THE SOURCE OF THE ROTATING BEACON WAS NOT DETERMINED.