They kept Charlie Ward, Kurt Thomas, and Latrell Sprewell around for quite awhile. Those three got big contracts as well, I believe. After those three, the next three players from the '99 squad in terms of playing time were Patrick Ewing (retired), Larry Johnson (ditto), and Chris Childs (played 12 games last season).
The Knicks DID keep those players, and that was the problem. The team finished four games above .500 in a strike-shortened season, finished fourth, and somehow made the finals. They weren't that good, but management decided they were a championship caliber club.
'99 Knicks Team Page....
http://www.basketball-reference.com/teams/NYK/1999.html