If you want to stick to pads, then I suggest trying to get a fightpad. There are a lot of ones out ther elike the SF4/Brawl pad. Capcom even released a new version of it that is 15% smaller so you may want to look at that.
I keep hearing nothing but good things about the Hori fighting Commander Pro so you may want to look into that one aswell.
Or if you want to stay with something similar, just get yourslef another Xbox pad. Although I suggest getting the one with the transformable dpad.