Windows 2003 Password Complexity

Hi,
I have a windows 2003 server w/ad. I also have a policy that is working fine. I would like to have users set passwords that have letters and at least one number in it.I see where I can enable the Password complexity in the policy, but I’m not sure on how to actually set up the password to use numbers and atleast one number. Any help would be appreiciated. Thank You