It just runs at a steady 30fps, which is about the same framerate as movies btw (sio who needs 100+ fps???).
Movies is a completely different matter. When something's interactive, I prefer it to run at at least 50 FPS, otherwise mouse controls, etc. seem to lag. Also, a 30 FPS movie has full "real" motion blur at all times, which means it has the equivalent amount of motion detail as a 100 FPS non-motion-blurred game I think. Although Crysis does include some sort of motion blur effect, I think it's mainly aesthetic (for fast movements, etc., rather than subtly conveying sub-frame motions).
But a 9800gtx is really good. You say you paid less than $1000 for your computer, but how much did you pay to upgrade to the 9800gtx? I was under the impression that these high end cards still cost ~$300.
Most non-hardcore PC users usually don't want to pay 40% more than what they need just for a gaming card. For serious gamers, it's another matter of course, and that's the whole point of the "PC gaming situation" - there aren't nearly as many "hardcore gamers" as there used to be (or there never were as many as they thought), and therefore there's not enough market for these high-end games to sustain them.
Remember though that this isn't just about graphics - it's about gameplay. The traditional M-rated "hardcore" shoot-em-up game may get all the publicity for it's flashy graphics and technical features, but that doesn't mean the gameplay (and content) appeals to everyone. I would bet the majority of gamers are tired of the endless Doom clones, etc. Otherwise, the Wii would have become a "niche" item, but it's quite the opposite, and I think this fact alone supports my theory very well.
Simply the fact that most games today are categorized into "genres" even before they begin development is a sign that there are hardly any more "revolutions" (rather than "evolutions") of video games these days. But that's another topic.