this post is derive from this link. this can be in microsoft excel 2007.
Click on the cell in the workbook where you want your drop-down list to appear. Cell A3 is active in the image to the left (click image to enlarge it).
Click the Data tab, and on the Data Tools menu, click on Data Validation. The Data Validation dialog box will appear.
On the Settings tab, below Allow, click the down arrow and select List.
For a simple list, type the items in the Source box in the order you want them to appear in the drop down, separating them by a comma as shown is the image. Click the OK button.
Now, at the insertion point, you can click the down arrow to display the options, clicking on one to select it.