The GTS is actually the lower end version of the 8800 iirc.
However, i'd say the requirements are for more medium settings as opposed to just running the game. My advice? Play the demo!
Also, the only reason why an 8800GTS has a chance in newer games is due to engine stagnation as a result of multiplatform games

So for the love of god people better not start complaining 'zomg unoptimized ma 4 year old gpu can't max!!1!!!'