3 spins out of 7/probability

I have some difficulties to find out the probability of winning 3 spins minimum out of 7 spin.
It's an interesting money management:bkr 99 units,win 29 units, if at least 3 W out of 7 spins.

Who has the answer?

I'll illustrate some details about it lat...

Linkback: http://www.rouletteforum.cc/index.php?topic=14502.0