I bought the first Garritan Orchestral Strings back in 2002.

Back then, IIRC, they were to be imported into Gigastudio.

Well, here we are in 2017, Gigastudio is defunct, there has been a "divergence" with NI and Kontakt and Make Music is talking about the ARIA player. But I can't find the player as a download or purchase option and, even if I did, I'm not sure these old libraries would work with it.

Is there any way to get these old GOS samples working again? More poignantly, is the ARIA player setup to import these older libraries?

Did those old versions come with a VST plugin?  Or, were they specific only to given hosts such as Finale or Sibelius (perhaps versions that existed before VST/AU/etc. were standards)?

If the thing has a dll plugin, you might can:

1.  Get it working in 64bit versions of Cubase with a 32bit Bridge.

2.  Get it working in a 32bit version of Cubase.

Short of using its own player, I don't think it'll be possible to 'extract' the programs/samples, at least not in any quick and obvious way other than getting it all running on some system and 're-sampling' the thing note by note.  For all the time and effort, you'd probably come out much better just upgrading to GPO5, which does have a lot of new content which is based on those early versions of GPO (Garritan Orchestral Strings, based on the old ADSR style of CC Automatable User Interface are a perfect example). 

GPO5 works in the ARIA player, which supports most if not all 32bit and 64bit hosts on Windows and Macintosh (and unofficially, some get it working under Linux as well).  It also supports scalia, for alternate tunings and non-standard scales.  ARIA is really lean and efficient.....and while it's not super obvious, it's actually very flexible in that you can tweak/extend the instruments directly via text editor (sfz format).  The samples themselves in GPO5 are kept as raw sample files...what little encryption that is done to them makes it difficult to steal the samples directly (phasing issues, normalization, pitch, and other stuff that ARIA corrects in real time), but they do stay intact enough that you can have a look in something like audiacity and discover accurate loop points and whatnot if you want to use bits and pieces of these samples to 'create your own' ARIA based instruments (of course you'd need to register GPO5).  For most users, there's no need to dig that deep into the libraries/engine, but it can be done.  I.E.  Maybe you hate the loop points chosen for an oboe sample, you could fix it.  I.E.  Maybe you want to make a new drum-map.  I.E.  Maybe you want to add an LFO to induce vibrato with a CC event.  I.E.  Maybe you want to 'layer up' more than one zone into a single instrument (build sections from single player samples).  I.E.  Maybe you don't like the way a particular zone is 'balanced' and want to increase or reduce the 'gain'...you could do all these things with GPO5.

Having said all that:  In my opinion it's best to simply upgrade to GPO5.  For the money, it's still a very good library.