Please excuse the mini-necromancy, but given the thread topic, I hope I can be excused.
Is Anselms argument for God as simple as since we can conceive of the existence of an omnipotent God, therefore he must exist?
That seems fundamentally flawed, or (more kindly) just wishful thinking.
No, I think Anselm's argument is more complex than that.
It's really an attempt to show that if you assume the non-existence of God, a formal inconsistency follows. So it runs something like this:
(1) If God does not exist, we can still conceive of God (as not existing).
(2) If God does not exist, we can conceive of something exactly like God, but existing.
(3) God is, by definition, the greatest thing we can conceive of.
(4) A thing conceived of as existing is greater than a thing conceived of as not existing (other things being equal).
(5) Therefore, if God does not exist, we can conceive of something greater than the greatest thing we can conceive of. Which is a contradiction.
(6) Therefore, God does exist.
So the argument turns not simply upon our ability to conceive of God, but upon our inability to conceive of anything greater than God, and the notion that this would lead to a contradiction if God didn't exist.