Drop Down List value to Hide Rows

I hope nobody minds I am reviving a dead thread but I am facing currently a similar problem:

I have an Excel 2007 sheet with a drop down list which looks like this.

\1
2014-04-14_172511.png

My plan is now that whenever someone picks the values CP320, CP320s or CP320n from the drop down list (marked yellow), the rows 12-14 (marked blue) will be automatically hidden. If the values CP321, CP321s or CP321n are selected the rows reappear.

I am pretty sure this can be done with a nice VB macro, however unfortunately I lack the skills to do it by myself. I've tried other approaches, like the one mentioned in this thread, but they all failed.

Anyone willing to help me on this one?