I finally got done installing the game, and tried playing a bit of it. I... just can't. The way Chris's hands move around all janky wherever I aim. Eughh, it makes it seems like the game's running at 15 fps even when it's benchmarking at 40-90 fps. The game seems pretty good, but the control with my mouse is just abysmal. Please, somebody a little savvy, tell me what I'm doing wrong, or do I really just need to go out and buy a gamepad? It's probably about time I get one, anyway.

Yes you do. A 360 controller makes that game the best version out there. Even though it lacks the gold edition content. Get a wired one since the wireless adapter is crazy rare.

There were 2 downloadable episodes that came out on the 360 and PS3 versions that aren't available on the PC.

USB 360 gamepad is always handy to have.

Yah there's really nothing you can do about the mouse sway,  Capcom thought maybe it would be too easy to use a mouse for aiming so they added a little breathing sway.  I got used to it though, i'd much rather have freelook controls than the controller camera control.

Having a 360 gamepad for your PC is a sound investment, I think.

I played the entire game using a mouse and keyboard.
 
With some rebindings so certain quicktime events weren't fucking awful.
 
It was just fine!

Did u try disabling Vsync? Lots of Console ports have problems when u activate Vsync. It just makes the whole game janky and you cant really tell why. Apart from that, did u measure constant 50 fps while playing or in the benchmark? When u play and u have fps drops it might cause an unsmooth experience too.

You can use your PS3 gamepad on PC, too. Might need some configuration for the game, but should work fine.
 
Though, IMO, this game's controls don't feel right whether you play with a gamepad or KB and mouse. They should have changed the control mechanics the moment they decided to turn this into an action game.

" @Olivaw: Wait, so it wasn't all jaggy and crooked when you aimed around? It feels like there's a huge load of lag or something. It responds quickly, but it's like his arms only pivot to eight different points in a circle.
@Marz: Really, man? Oh god. I'm playing in hard mode, and the first long-necked chick zombie thing you fight is just a bitch with that breath-sway. Along with the other zombies stampeding at me, I feel like don't even have control. "