While the PC version of Street Fighter IV is lagging months behind its console brethren, the core codebase for the computer version is actually much, much older. The arcade game from which the PS3 and Xbox 360 games are derived is based on PC architecture, so in essence this home game is an enhanced rendition of the "real thing". That being the case, it's equally as brilliant as the console games in terms of the raw gameplay, but the graphical assets can be scaled up to whatever your system can handle. For the Street Fighter IV purist (and we know how many of those there are), the difference could be remarkable - I mean, kit yourself out with the right equipment and you can play SFIV at 120FPS if you want. However, for the rest of us, the improvement will be marginal at best.
As it is, the arcade board on which Street Fighter IV was designed is somewhat underpowered by enthusiast standards. Designed to be cheap to build and even cheaper to fix should something go wrong, the spec is exceptionally modest - a 2.13GHz Intel Core2Duo CPU powers the show while a 256MB GeForce 7900GS provides the visuals, which are rendered at 720p at 60 frames per second.
This gives you some idea of the base spec that'll give you arcade-perfect gameplay. Capcom reckons you'll get something playable on a 2.0GHz Pentium 4 with a GeForce 6600 GPU (yeah, good luck with that), but what is interesting is that its maximum recommended spec remains light - a 2.0GHz Core2Duo with an 8600GT. That said, there are a range of additional graphical options and post-processing features built into the game and amusingly, should you ramp absolutely everything up to the limits and run at 1080p, the built-in benchmark program still manages to rate my Core i7 set-up with top-of-the-line GTX295 as merely "efficient", with a B rating. However, as you'll see later, while the options can impose exponentially larger loads on the GPU, the actual visual results shows only minor improvements over the console game.
To illustrate, here is a comparison video showing the game running at 1080p on the Core i7 set-up, up against the Xbox 360 version, rendering internally at 720p before the Xenos GPU blows up the image to "full HD". One pixel in the player here is one pixel on the 1080p display so there is some pretty brutal cropping. If you can handle it, definitely check out the HD version, which has more real estate to play with.
The comparison also serves to illustrate just how good the Xenos scaler actually is: GBP 130 console versus GBP 1200 PC, and there's not really much in it is there? Texture levels are clearly optimised for the original 720p display, and aside from the jagginess in the edges, and the extremely basic shadowing, the Xbox 360 version is a close match. During actual gameplay, the PC version does have a clearer edge though - more detail is retained in the fighters and backgrounds, you can try the game out at frame-rates that exceed 60FPS (if you have the monitor to support it), motion blur can be tweaked to your liking, plus the impact of superior anti-aliasing produces a far clearer, less shimmery image.
You can also take your pick from a range of different post-processing effects. There are three of these in total: Ink, Watercolour, and Posterisation. Typically they concentrate on shadow and edge detail, and while there is no tangible advantage in using any of them, they do clearly change the style of the visuals and it's nice to have them there to tweak with. Here's another comparison video showing the normal mode versus all three filters.