0000807249-01-000056 SC 13D 1 20010205 ACNIELSEN CORP 0001019878 8700 061454128 DE 1231 SC 13D 34 005-47591 1525159 177 BROAD STREET STAMFORD CT 06901 2038344200 177 BROAD ST STAMFORD CT 06901 GABELLI FUNDS INC ET AL 0000807249 0000 133056041 NY 1031 SC 13D ONE CORPORATE CENTER RYE NY 10580-1434 9149215128 GABELLI FUNDS ONE CORPORATE CENTER RYE NY 10580 SC 13D 1 0001.txt INITIAL SCHEDULE 13D