Operating On Neighboring Rows In A Column

Hi Folks,

I'm just learning Transact-SQL, so pardon if this is a dumb question. I would like to perform operations on neigboring rows in a database table column, and I have no idea how to do this. Say I have the following table:

Date (smalldatetime) | Value (money)
date1 | value1
date2 | value2
...
dateN | valueN

What I would like to compute is:

average(value2 / value1, value3 / value2, ..., valueN / valueNminus1)

How would I pose this as a transact SQL statement?

Thanks,
Adam Cataldo

(If it helps, I'm running SQL Server Express 2005)