Two GPUs are used here in concert with a base-level i7 at 2.66GHz: the GTS250 lower end enthusiast card (also known as the 9800GTX) alongside a top-of-the-line GTX295. At 720p, there's actually no point showing the video - performance is entirely identical. Here, at 1080p, we see that the GTX295 runs at max frame rate while the GTS250 hits a minimum of 44FPS, but still manages an overall average of around 58FPS. This is v-synced too. If you're looking for a sustained frame rate, a quick tweak of the config file seems to be able to cap frames, so you could limit yourself to 30FPS if that's what you want, but I'm not sure I'd recommend it - the benchmark seems to put more stress on the GPU than in-game action does.
Batman: Arkham Asylum doesn't exactly tax the CPU either. I'd say that just about any decent dual core CPU should run the game just fine, and a 9800GT/9800GTX/GTS250 level of GPU should give you an excellent performance at 1080p60. In fact, one of my colleagues has had a console-bettering experience using a 1.8GHz Core 2 Duo and NVIDIA 7950GT, meaning that even much older PCs stand a great chance of running this game very well indeed.
For those willing to invest a bit more cash into their PCs, there's also the matter of PhysX support, which comes in two flavours. The "normal" level is tailored to those using higher end NVIDIA GPUs - specifically the GTX260, or better. Additional effects you'll see in the video are added to the scene, and in some cases, the difference is visually quite dramatic. However, at "high" level, Rocksteady has really gone to town on the effects - so much so that using a single GPU is effectively disastrous, giving slideshow like performance. Indeed, the developer recommends that you have a 9800GTX level card in addition to your main GPU simply to run the physics, and here's a sampler of what you get:
There are some very nice effects: volumetric smoke/gas pervades the asylum, adding to the atmosphere, and it has gameplay uses too, providing additional cover. Paper and cloth are emulated nicely, tiles smash, scenery crumbles and there are some major bonuses in the Scarecrow's nightmare visions. It's by no means essential to the gameplay experience, but it is impressive, it is exclusive, and at times the impact is striking. The PC version already has clear graphical advantages over the console offerings, and this adds additional loveliness to the proceedings that are very welcome indeed.
The disadvantage is that depending on the GPU, performance is impacted significantly with PhysX enabled in "normal" mode - to the point where to maintain 1080p60 you really need a second graphics card dedicated solely to the physics calculations. Now we're starting to talk serious money, but at least SLI users can deploy their hardware in a different fashion to get the top-end experience.
I'm very much an advocate of the PC as the "fourth console", with the platform having just as much right to sit under your HDTV as the Xbox 360 or PC. Indeed, for those with 1080p displays, the PC is just about the only hardware available capable of offering a true "full HD" experience on virtually any game. But my recent experiences with console conversions have left me a little cold: the interminable delays waiting for the games to appear months after the Xbox 360 and PS3 versions is bad enough, but poorly performing software for those with top-end kit is shocking.
Batman: Arkham Asylum on the other hand does much to restore the faith. It is palpably and measurably better than the console versions and I haven't had to wait three to six months to play it. It generally looks better, has more in the way of bonus bling (depending on your hardware) and crucially, being able to run the game at 60FPS has a tangible, positive impact on the gameplay.
Controller lag is noticeable on the console versions, more so than on other Unreal Engine titles I've played. It's still there running at 60FPS on PC, but it is significantly reduced to the point where the Xbox 360 and PS3 versions feel rather sloth-like in comparison. More than that, the "FreeFlow" combat system greatly benefits, feeling far more responsive and enjoyable to use than on console. Put it this way: you wouldn't want to play Tekken or VF5 at 30FPS, and after enjoying Batman combat at 60 frames, it's very difficult to go back.
Whether it's down to the Unreal Engine underpinnings, or simply Rocksteady's efforts to get the most out of the platform, the bottom line is that the PC version makes a great game even better, and you don't need prohibitively expensive hardware to get a top-class experience. As a textbook example of a cross-platform project that exemplifies the PC's performance advantages, Batman: Arkham Asylum is absolutely superb.