Hi!
THis week I picked up the second core box set for the Federation Commander game system, Romulan Border:
This box lets you mess around with differnet classes of Federation ship to those in Klingon Border, and has you facing off against the pointy-eared wannabe galaxy-conquerors!
Plus the Gorns (big reptilian chaps, if you aren't familiar with them) and a giant space dragon are included, to boot!
Basically, each core box set for Fed Commander lets you use the same ships (with the updated version of Klingon Border's rulebook - rules for Romulan weapons weren't in the initial release) but give you different warships and starting races.
However, you can still get the lanimated ship cards for races you don't get in the box and use the latest version of the rule book (included with Romulan Border and recent shipments of Klingon Border, available as part of a trade-in of your old rulebook if you get an older KB box).
Compared to Star Fleet Battles, it's a lot quicker to play (there's a list of differences between the two in the links at http://www.starfleetgames.com/fc/ - asd well as a pdf with a demo of the game system)
Gary