There will be certain circumstances in which trying to open a dts designed in sql 2000 will cause an error in SQL 200 DTS Designer components. According to microsoft these condtition will cause an error when trying to do this.
•The SQL Server 2000 DTS package was last saved from an instance of SQL Server 2000 that is running on a Windows 2000-based computer.
•The SQL Server 2000 DTS package is stored in a structure storage (.dts) file.
•The SQL Server 2000 DTS package is modified from an instance of SQL Server 2005 that is running on a Windows Server 2003-based computer or on a Windows XP-based computer.
The fix for this can be found in knowlegde base article 917406. Here is the link with the two possible solutions http://support.microsoft.com/kb/917406
Farayi