If there is something that's much faster
and cheaper than SSDs, it's probably 5 years away

. For the foreseeable future, SSD is the future of fast storage on laptops/desktops. When any new technology comes around and supercedes it, it probably won't be cheap either since it'll have a performance advantage and low volumes (just like when SSDs, Plasma screens, Blu-Ray drives first came and replaced older technologies).
Your list of games isn't very demanding. Your system is perfectly fine for all of them except Mafia II with MSAA+PhysX.
BTW, Braid is cool game. You should check it out. And also, you don't have Bioshock, Half-Life 2 on your list. Those are almost a must-play I would say.