For a simple usage, this could be an aproach.
PHP Code:
$salt="some_key_here";
$salted_passwd=md5($PHP_AUTH_PW.$salt);
$sql="select * from adminuser where admin='$PHP_AUTH_USER' and password='$salted_passwd'";
that way, if your database is compromised so the lurker can figureout someones passwd, they might be able to find something that mathes the md5-sum, but they'll never find the real passwd because you salt the submitted one, befor you check it up against the one in the database. Which would make a compromised one
double salted, befor you check it against the lurked one.