I just cannot use ws or something like that for forward and backward, I just hit them both too much. In 2002 someone told me what she used for Counter-Strike, so I tried it and still use it today. I'm not pro at any fps or anything, but the config I use lets me actually play and move. Here's my setup that divides movement to each hand (left/right on the keyboard, forward/backward with the mouse):
http://redscarlet.paragonsigma.com/l4dcontrols.png
My left hand normally rests on, from pinky to thumb: left control, left shift/capslock, a, s, left alt/spacebar. I just shoot with my pinky instead of click. I use that setup in CS/HL/HL2/Portal/L4D/L4D2/Bioshock and any other fps I'd play.
There's no telling what will work for you, but if movement is your issue like it was mine, there's who knows how many combinations you could try to find one that works out for you.