Does it
have to be the Dos version? C&C95 (which works fine on Windows XP) can be found there:
http://www.megagames.com/freeware/co...?tab=downloads
(E.A. seems to have removed the download from their official site...)
And there might be some downloads of interest at the bottom of this page:
http://portal.commandandconquer.com/...ium/downloads/
... I found KKND Extreme (according to Wikipedia a polished up version of the original) over at Dos Games Online - the download is only 7.37 mB big however, so I assume this is not really the full game. Nevertheless:
http://www.dosgamesonline.com/index/...D_Extreme.html
addendum:
As Luchsen pointed out just below, it seems to be quite futile to look out for anything better regarding that particular game.