an answer in one cell unhides rows - possible?

Hello, I suppose there is no such thing as a quick question (although all those who have helped me previously have proven this wrong), but please read on.

I am adjusting/adding to a previously 'built by someone else' pricing calculator. Is it possible to have the following function?

a drop down list on cell G5, gives you the options of yes or no. If you select yes, rows 120:123 (inclusive) are unhidden. If you select no, the same rows are hidden.

I'm thinking this maybe more of a vb code solution but not sure what to do.
I will wait patiently for your help

Cheers guys

A gentleman and a scholar, thank you for this - works perfect

Just a quick one though, could you run a second code almost the same as this on the same worksheet? If so, how?

Does anybody know how I would do this if I wanted to run this same code for the same page, but different rows from a different input cell?

Thank you for this p24leclerc, they won't let me give you rep, but this is perfect