Assassin's Creed on 2010 13" MBP (bootcamp)
Given that the thread has meandered a bit, thought I would chime in.
On Win 7 32bit (specs in sig), installed Assassin's Creed through Steam on Saturday (had purchased Ubisoft 4 pack deal weeks ago). For the record, running the NVidia 266.58 driver (Windows Experience Index is 6.1 for gaming and 5.4 for Aero).
Totally engrossed by the game. Never played a game like it before (never owned a console or played console games much).
I've played it with settings maxed out and think it looks beautiful and is completely playable. Possibly not buttery smooth at max settings, but for the kind of game it is, absolute butter doesn't seem necessary. All the eye candy helps realism.
Played with the settings a bit and using FRAPS got a bit of an idea of fps and different settings. At max settings with AA off it averages around 20 fps, bumps up to about 25 fps in areas with little going on, and can go to 13 fps in high congestion areas or at the top of towers. The thing is, I don't notice a difference in gameplay with changes of frame rate: i.e- at the top of a tower if it shows 13 fps, I can still look around the city below and not notice any drop or lag in performance, even if moving the mouse quickly.
If I drop the settings to one notch above the lowest, it seems to average around 25, and again, without noticeable change in performance. If I put all settings at low, frame rate jumps to the upper 30s, and I think I can notice some increased smoothness when looking around quickly.
So, I don't get it. fps is supposed to be this magical number, so why can't I notice that much difference in how the game plays despite "mediocre" frame rates? One thing I do notice, which makes total sense, is that in cut scenes the audio lags behind the video. But, it seems a small price to pay for everything to look so nice.
Is FRAPS inaccurate, or for non First Person Shooter games is frame rate not as much of an issue?
I've played King Arthur: the role-playing wargame and Call of Juarez through Steam as well. King Arthur I played maxed out, which seems to run about 12/13 fps and I can notice the difference in battle scenes if I lower the settings, but again, for the type of game, doesn't matter much (I don't think, could be wrong). Call of Juarez I think I played maxed-out, too, and seemed smooth, but I think the requirements for it are pretty low.
Thought I would add my experiences. I think I have a ways to go in Assassin's Creed, but am considering ACII 'cus it is just so neat!

Thinking in Boot Camp it could play decently at more modest settings.
Happy gaming, all.