Thanks, Tommy! I don't have SQL2000 available to test, so I had to go by the documentation. And the description of the effects of ROLLBACK in a trigger is word for word the same for the current version and for SQL Server 2000.

See http://msdn.microsoft.com/en-us/library/ms181299.aspx and http://msdn.microsoft.com/en-us/library/aa238433%28SQL.80%29.aspx.