Insert Formulas into an Excel Column from ms Access 2007.

I'm using Access 2007 vba to manipulate an Excel spreadsheet.  Column A contains a column header: "Dates" and the rest of the column contains dates up to the first empty cell in that column.

I need to iterate from A2 thru the last date and - based on the date - place one of two formulas into column "N" of the same row.   If date is before 1/1/2004 I put one formula, else I use a different formula.

Can someone give me a  rough algorithm with the appropriate row/cell/range related functions to accomplish this?  I have code to determine the STRINGS that represent the formulas relative to the rows they will be placed into.

I'm referencing the Excel Object Library and already have quite a a bit of working code which manipulates, formats, inserts columns, sorts, etc, etc, so I'm not totally inexperienced.  Just need some hints :-)   Thanks!