I used to straighten my hair about once a year with the straightener you get at the salon- the kind that will put blisters on your scalp its so strong.  I finally stopped doing that due to the damage to my hair and because I have completely different curls now.  I still have naturally curly hair- but it is forever different than it once was.  I have ruined my hair- for all you girls out there who think you want straight hair- stick with the big round brush, hairdryer, and straightening iron.  That way you get to keep your gorgeous curls, but can go straight too.  I have to wear my hair straight all the time now, due to the curl being so unruley now.