I just confirmed that KFW 2.6.4 does indeed import tickets from a 
Windows XP SP2
system configured to authenticate against a MIT 1.3.3 KDC.

I will need to build a 2000 system to test.

Note: Tickets will not be imported if they are of a type not in your 
default_tgs_enctypes list.
Please confirm that you are not excluding the necessary enctypes.

P.S. This is not a kerberos 5 issue.  The report should have been made 
to kfw-bugs@mit.edu