Here's a template that uses Excel 2007 to HELP solve Sudoku puzzles. It doesn't actually solve the puzzle for you, just helps you keep from entering duplicates by highlighting them when entered.
You could also you use it to create your own puzzles.
http://office.microsoft.com/en-us/templates/TC300003871033.aspx?pid=CT101441811033
[cross posted with the general forum]