0000950133-00-003325 424B3 1 20000810 COSTAR GROUP INC 0001057352 7374 522091508 DE 1231 424B3 33 333-39490 691334 2 BETHESDA METRO CENTER 10TH FLOOR BETHESDA MD 20814 3012158300 2 BETHESDA METRO CENTER BETHESDA MD 20814 424B3 1 e424b3.txt COSTAR GROUP INC. FORM 424(B)(3)