What specs exactly are you no longer exceeding? RAM and CPU are easily the most important for Sins, but you should be able to run at least the smaller maps on trinity if you could do so on original Sins.

Rebellion has a major lighting and particle effects overhaul, so it will be much more demanding on your graphics card, in addition to the above.

No, the maps are pretty much the same. Its just that if you could run an 8 player 65 planet map without the expansions without performance troubles you might get lag with 6 players and 50 planets with the expansions. That said its really hard to predict how individual computers will react.

Well I bought the game off steam. I love it, but starting it directly from Steam doesn't work. Everytime I try to, the game crashes and I get a weird message giving me something about a minidump. It's something like C:users/Leandro/appdata/local/temp/sins dump/sins-diplomacyv1.34-2012-03-05-22-30-16-1620-1456.dmp

If I go to the actual game directory it works, but I want to play it off Steam. Any idea why this occurs?