Poisson vs. normal approximation

This is just a homework problem from the text that I can't seem to set up right.

Assume that the background noise X of a digital signal has a normal distribution with $\displaystyle \mu = 0$ volts and $\displaystyle \sigma = 0.5$ volt. If we observe n = 100 independent measurements of this noise, what is the probability that at least 7 of them exceed 0.98 in absolute value?

How would you use the Poisson distribution to approximate this probability?

Or the normal distribution to approximate this probability?

Thanks in advance. I was just wondering how one would go about setting this up.