How to populate a listbox using a combo box

[Jeff]

I want to populate a listbox by using either a textbox or
a combo box. I have a listbox that displays first and
last name. What I want to do is type the some letters and
the listbox will repopulate. Simaliar to how a combo box
works. For example If I type s in the textbox or combo
box it will display all of the names that start with s in
the list box. I would greatly appreciate the help.

Thank You
Jeff