Modify OSPF default metric learned from BGP

Hi all. I have two WAN connections, one terminated with a 2811 and the other with a PIX. I am redistributing the default route into OSPF. On the 2811, the default route is being learned via BGP. How can I adjust this BGP-redistributed route to be preferred over the route via the PIX? When I do a show ip ospf database, both routes are in the table, but the devices are choosing the closest path out. (Default OSPF behavior.) When I do a show route from several switches, the administrative distance and metrics are equal for these routes. Any help would be appreciated. Thanks.