[DougOzzzz]

I thought I posted this before but it didn't show up... anyway, here is what the Excel spreadsheet looks like:

4 columns -

Column A has goals scored, from 0-20.
Column B has the formula =POISSON(A1,0.9,false) The A1 will change based on the current row.
Column C has the formula =POISSON(A1,2.0,false)
Column D has the formula, starting in cell D3, =C3*SUM(A$1:A1). The first 1 following the dollar sign remains constant, while the 2nd 1 will always be the current row minus 2. The sum of column D is the total probability.