I think I see the check box you mentioned, however, Ent mgr crashes when I set up the package:
I set a source of SQL db, a destination of Text file, and create a TransformDataTask. On the destination tab, I click the Execute button. No fields appear in the list, which means it won't let me go further. So I click the Define fields button. Then it crashes with a mmc.exe caused a memory fault.
I have SQLSrv 2000, sp3. I'll look for info on this problem. If anyone knows the answer, please let me know. Thanks!