The NCA patch is an add-on that gives the player about a dozen new craft to play with/against. Things like the E-Wing, the Tie Phantom, etc... Lots of good stuff. I highly reccommend it. You can download it here: http://www.the-sfa.org/SFATech/
BTW, this patch *adds* craft to your game. It does not replace existing craft.
Give a man a fish and he will eat for a day... Teach a man to fish and he will sit in a boat and drink beer all day.