Hey arachnoid - make sure that you are in the "This Workbook" object when you type in the code from Loomah. You can get to this by going to the tools menu, selecting macro and then clicking on Visual Basic editor. On the left, you should see VBA project with the Excel objects listed (Worksheet1, Worksheet2, Worksheet3 and This Workbook - by default).
Double click on This Workbook to open the code window. Then type in Loomah's code or use the object selectors (drop down lists above the code window) to select Workbook from the left drop down list. THis will generate the code stub for the open event.
If you are still having problems or if you have already done this, copy and paste your code in the reply - there may be a problem with the code you are trying to execute.
Hope this helps.
Jay