i overhauled my 92 system with 6.5 rear and 5.25 front with the stock enclosures. here's some pics.
http://home.twmi.rr.com/thetempest/aud_mtspkr.html
(this site will be moved mid-December)
dunno how different your 96 system is. as far as replacing just the speakers, i'm not so sure how much of an improvement you will get. you'll have to buy that AudioLink adapter found in the "reviews" section, or some comparable interface.
like you pointed out and probably were inferring, you can always improve upon the Bose by replacing the entire system, but hey, it depends on what your listening requirements are and how deep your wallet is. :)
as for me, i replaced my entire system with a sony MP3 player (cheap CD changer to me) and Polk components all around. as hindsight i might've gone with the Alpine MP3. didn't have the cash for an external amp.
[Modified by tempest, 9:21 PM 11/30/2001]