Thanks for the how-to! I've been using Windows 7 for a long while, but this is one thing I hadn't thought of until just a few minutes ago. I was scrolling through my All Programs menu and a light bulb came on. Why is my start menu so short when my screen is so tall???
One thing to note is that 18 is not necessarily the tallest. This depends on your screen resolution height and whether you have "Use large icons" checked in the Customize Start Menu box (not to be confused with "Use small icons" for the taskbar).
To get the most room for your All Programs menu, enable the large icons and set the number of recent programs to 30. Keep in mind that my screen height is 1600 and it reaches about 80% to the top.
Author may want to add this information to the article. Cool stuff!
Regarding myzr7's report of recent programs not coming back, it does clear the list when you untick and apply, and your list starts blank when you turn recent programs on again. This behavior seems normal for me. But then another explanation might be that this thread is 2 years old and there really was a bug but they have since patched it. Either way, it's working as expected.