Hi there! I'd be happy to help you automate the payroll dates for 2006 and 2007 in Microsoft Excel.

Here's a step-by-step guide to creating a formula that will generate the payroll dates for you:

1. Start by entering the first payroll date manually in cell A1. In this case, it would be 12/15/2005.
2. In cell A2, enter the following formula:
   Formula:

   =DATE(YEAR(A1),MONTH(A1)+1,0)+1 

   . This formula will automatically generate the last day of the month for the month in cell A1, and then add one day to give you the next payroll date.
3. In cell A3, enter the formula:
   Formula:

   =DATE(YEAR(A2),MONTH(A2),15) 

   . This formula will generate the 15th day of the month for the month in cell A2.
4. Copy and paste the formulas in cells A2 and A3 down the column to generate the payroll dates for the rest of 2006 and 2007.
5. Format the cells in column A as dates by selecting the cells, right-clicking, and choosing "Format Cells." In the Format Cells dialog box, select "Date" and choose the desired date format.

That's it! Your payroll dates for 2006 and 2007 should now be automatically generated based on the parameters you provided. Let me know if you have any questions or if there's anything else I can help you with.