I am a 40D, and bought a 42C the first time around.  The 42 was perfect, but the cup size was still a little big - so I also ordered a 42B, which is much better!  The bra is incredibly supportive, comfortable, and keeps my stomach sucked in!  As other reviewers have stated, it does sort of give you pointy boobs, so if you are going to wear a thin shirt, this may not be a good bra choice.  However, with formal dresses made of thicker material - it is amazing!  I will never wear another strapless bra again, I'd give this 10 stars if I could.