Well, I'm assuming you didn't buy a MadCatz Fightpad or an arcade stick along with the game, so you're stuck with the regular Xbox 360 controller. Working that analog stick through QCFs, QCBs and other assorted moves will take a toll on your left thumb, no doubt.
I'm always up for a throwdown if you or anyone else with SFIV on Live want.
have a suggestion for the lf poll? pm me