Sorry I wasn't going to post again but I don't like my involvement in having produced this final (now penultimate) response.  olePigeon, et al., if you read up in the thread you will find correct statements of the actual law.  What you're citing there was a 2006 suggestion that has been superseded.  If you actually search 17 U.S.C. § 1201[which I've summarized above] (a)(2) you'll find:

"(2) No person shall manufacture, import, offer to the public, provide, or otherwise traffic in any technology, product, service, device, component, or part thereof, that--
(A) is primarily designed or produced for the purpose of circumventing a technological measure that effectively controls access to a work protected under this title;
([b )] has only limited commercially significant purpose or use other than to circumvent a technological measure that effectively controls access to a work protected under this title; or
([C )] is marketed by that person or another acting in concert with that person with that person's knowledge for use in circumventing a technological measure that effectively controls access to a work protected under this title."

And as I noted above in the thread, the outgrowth of the exception you cited (as it is actually law - 17 U.S.C. § 108( c )) really only refers to libraries or archives who previously had possessed physical copies on formats that require machines to display said works (i.e. software) that are no longer available unused at fair market prices.  In other words, if one possessed System 7.1 but you can't get a machine unused at fair value to so display, you can create a digital copy (subject to harsh user-restrictions).  However - and again none of this has been litigated - the presence of emulators severely complicates the law, particularly given its legislative intent.

I'm likely going to write a 'note' (for a law journal) on this subject surveying the legality of vintage collecting.