A common complaint about the Xbox 360, particularly when discussing old school games or fighters, is that the d-pad on the controller is awful and makes it harder to play these types of games. The problem comes from the fact it is one solid disc rather than split into separate buttons, which makes it hard to be precise.
Microsoft has tried to address this with a new controller, released in November 2010, that features a transforming d-pad that you twist to raise the cross part of the pad higher so it is easier to press with precision. It isn't perfect, as some core issues still remain (diagonals still don't register 100% accurately) but it is better than what we had.
Read our full review of the new controller here.

Comments
That is your advice? Use the stick? REALLY? As is, the 360 is useless when it comes to fighting games (if you are anything more than a scrub). So what should you do? Go mod your pad or get a PS3.
The mods aren’t that hard and almost all of them work. Seriously, it is better to do something about it than to just be beaten down by dumb design.
Or…
Like I said you can buy a PS3 and play all your fighting games there. This will also let you play the enjoyable exclusives on the system.