Unfortunately Excel 2008 no longer supports Visual Basic. VBA has been replaced by Applescript in version 2008 for the Mac. If you try to open a worksheet that has a VBA macro you will be prompted to either leave the macro or remove it, but in both cases it won't run. Here is some more detail about this new feature.
Hope this helps. Let me know if you have any questions.
Again, Excel 2008 lacks the ability to record AppleScripts, so you will have to write everything from scratch. However, if you are familiar with applescript you can use the Automator workflows to activate actions from the Scripts menu within Excel.
If you have workbooks with macros and if you are already familiar with vba macros your best option is to do what most macro users have chosen to do and that is revert back to Excel 2004.
Hope this helps, and please don't forget to click the green Accept button. Thanks