Creating a drop-down list & selecting multiple items

I'm working with Excel 2007, and I'm trying to create a drop down list that I can select multiple items from, and have them appear on my sheet. I've gone through Excel Help, and I'm completely LOST.

Example list.

1.) This proposal includes 10 trees.
2.) This proposal excludes 10 trees.
3.) This proposal excludes all concrete.
4.) This proposal excludes all work shown outside the limit lines.
5.) This proposal includes all work as indicated per the client.

I would like to be able to see this complete list, in a drop down menu; and pick items 1, 4, & 5 only to show on my sheet. Any help would be greatly appreciated!