Transition Tab

Replaced in 2007

Saving

Save Excel files as - Allows you to change the default file type used when saving your workbooks. Make sure your file type is "Microsoft Excel Workbook" to ensure that your workbooks are saved in the most recent version of Excel. (Save tab, Save Workbooks - save files in this format)

Settings

Microsoft Excel menu or Help key - This is the key that can be used as an alternative to the Alt key to activate your menus. The slash key (/) is the default. (Advanced, Lotus Compatibility - Microsoft Office Excel menu key)
Transition navigation keys - This changes all sorts of navigation keys and how formulas and labels are entered. Useful if you are a user making the transition from Lotus 1 2 3 but otherwise do not have this checked. (Advanced tab, Lotus Compatibility Settings)

Sheet Options

Transition formula evaluation - Opens and evaluates Lotus 1-2-3 files without losing or changing information. With this option selected, Microsoft Excel evaluates text strings as 0 (zero), Boolean expressions as 0 or 1, and database criteria according to the rules used in Lotus 1-2-3.
Transition formula entry - Converts formulas entered in Lotus 1-2-3 release 2.2 syntax to Microsoft Excel syntax, and makes names defined in Microsoft Excel behave like names defined in Lotus 1-2-3.