Access 2003: rank with partition by

[MSIsam]

Below is an example of some data that I would like to rank using MS access. It would be similar to using the window funstions of other database applications. Does anyone know how I would create an expression to come up with DATE_RANK?

CUSTOMER  DATE_OF_PURCHASE [b]DATE_RANK[/b]
LARRY        01/01/2006            [b]1[/b]
LARRY        02/05/2006            [b]2[/b]
LARRY        02/10/2006            [b]3[/b]
CURLY        05/01/2006            [b]1[/b]
CURLY        07/01/2006            [b]2[/b]
CURLY        07/03/2006            [b]3[/b]
CURLY        01/01/2007            [b]4[/b]
MO           01/01/2006            [b]1[/b]
MO           01/02/2006            [b]2[/b]
MO           01/03/2006            [b]3[/b]

Any Help would be greatly appreciated.