select multiple items in asp.net listbox from code

Question

I have two databound listboxes. The first only shows items that have been assigned to my product. The second listbox shows all available items. What I want to do is select all of the items in listbox 2 that list box one contains.

For example:
ListBox1-
Item 1
Item 3

ListBox2-
Item 1 (Selected)
Item 2
Item 3 (Selected)

Code I have:

List<string> myList = new List<string>();
            foreach(ListItem f in ListBoxSourceDetail.Items)
            {
                myList.Add(f.Value);
            }
            myList.ForEach(delegate(string n)
            {
                ListBoxSourceEdit.SelectedValue = n;
            });

Answer 1

I figured it out, I was over thinking it... Loop through each list item in the first box and then find each matching result in the second table to be selected.

foreach(ListItem i in ListBoxSourceDetail.Items)
        {
            ListBoxSourceEdit.Items.FindByText(i.ToString()).Selected = true;

        }