My question http://superuser.com/questions/719083/does-copying-all-cookie-txt-files-from-xp-to-win7-work is based on the mis-assumption that the .txt cookie files must have been generated by FireFox (see body text). 

Thanks to the commenters that became clear.

Now what do I do - delete this question because it was based on an incorrect assumption, or leave it because there may still be value in the thread. I can imagine others may have the same confusion.

Maybe add an answer?