Nicley put Rich, very well said. To piggy back, if I may, one of the problems with this sort of ontological argument is it by implication posits a standered for perfection outside of God. For instance we, finite sinful humans, concieve of what "perfection" is and than compare our christian concept of God to that. This is unfounded because God by His self-revealation defines, philosophically or otherwise, what perfection actually is. This is not to say that this sort of argument is not on to something, obviously God is perfect, but only that we don't know what perfect is apart from God's self revealation, which is presupossed at this point.