Problems with date configuration

Hi, I had an application in which I used postgres 7.4, and then only thing
refering to date was:

datestyle = 'ISO,European'

everything else was commented. Now I have had to change the OS and I've
installed postgres 8.1.3, but this configuration is different, it's
something like:

lc_monetary = 'en_US.UTF-8'
lc_numeric = 'en_US.UTF-8'
lc_time = 'en_US.UTF-8'

and evrything else is commented, including the line which references the
datestyle. But in the comment it says #datestyle = 'iso, mdy'. Someone can
help me to make it works in the same way?

Thanks.

Fabi