Yeah, I'd highly recommend getting a controller for this game if you don't have one. If you have a 360 controller that'll be easiest; I use a PS3 controller with MotioninJoy.
I wouldn't recommend trying to play with keyboard and mouse... you can't rebind the mouse keys, or get rid of the mouse cursor ingame (but DSfix fixes that) and moving the mouse changes your lock-on target so it's pretty useless in combat. If you're gonna try using a keyboard, I'd recommend using keyboard only, the mouse is mostly useless since you can lock-on anyway. But you're better off using a controller, the game is designed from the ground up to be intuitive with a controller and it feels much more natural that way.
My Steam name is Brion Foulke, if anyone wants to try playing co-op in Dark Souls just let me know, I have a lv25 character and a lv10 character I just started.