Drop Down Lists in Excel 2007: To limit entries to certain items that you define, you can create a drop-down list of valid entries that is compiled from cells elsewhere on the worksheet. When you create a drop-down list for a cell, it displays an arrow next to that cell. To enter information in that cell, click the arrow, and then click the entry that you want. You can used the named range to create a drop down list.
Name a Range: Select the cell, range of cells, or nonadjacent selections that you want to name. Click the Name box at the left end of the formula bar. Type the name for the cells, for example, PARTS. Press ENTER.
To edit range of lists for drop downs:
formulas > Name manager>Parts, then highlight the list of parts as far down as you need.
To create or edit a drop down list, select the cell the list is to be in (B3), then go to Data > Data Validation.
Under Allow: select List.
Under Source: select the range of values that you want by either highlighting a group of cells (shown here) OR by typing the name of a named range (below).