0001036050-01-500649 DEFA14A 1 20010516 SEI CORP 0000350894 6211 231707341 PA 1231 DEFA14A 34 000-10200 1641332 1 FREEDOM VALLEY DRIVE OAKS PA 19456-1100 6106761000 1 FREEDOM VALLEY DRIVE OAKS PA 19456-1100 DEFA14A 1 ddefa14a.txt DEFINITIVE ADDITIONAL MATERIALS