You can embed a PDF file into a cell of an Excel worksheet and then use Excel's security features to lock the object. This allows you to take advantage of both technologies.

Office 2011 brings Visual Basic for Applications (VBA) back to the Mac. If you haven't used VBA before, and don't know why you would, here's a good example of how simple and useful it is.

Microsoft Excel is a spreadsheet program used for analytical purposes. The program's files are known as workbooks. A workbook should contain at least one visible worksheet--a collection of cells ...