Sorry but I'm late in responding. I must clarify my positions, especially on what I meant (but wrongly explained) when I said "natural grace".
"I acknowledge one baptism for the remission of sins"
As you can see, dear Marduk, baptism is not for the cleansing of original sin, but for the remission of sins. The Creed is here extremely explicit in affirming how being not in a condition of "full" grace - as the non-baptised infants are - doesn't mean you're fully disgraced and outside of God's friendship. Afterall, even your "souls of purgatory" are friends with God but still imperfect...
The RC extremely pessimistic position on original sin once implied that children were condemned to limbo, a region of hell, because of Adam's sin and not for their own sins. To stop this belief, Pope Benedict XVI had to invent the doctrine that God must give some extraordinary grace to the infants to prevent them from being condemned. Our position, on the contrary, stating that we have two major consequences of sin (death and concupiscence) which lead us automatically to sin, doesn't even touch the problem of children's destiny: we know God is their saviour too. Jesus himself says we must be as children to enter the Kingdom of Heaven, showing that children are "pure enough" (but not perfect) to merit salvation from God's perspective.
Our interpretation of a non-total depravity of human nature at conception also explains why baptism of children is not only necessary, but even possible. They need baptism for the *future* sins they are bound to by concupiscence, and at the same time they *can* be baptised because they experience a natural orientation (which I wrongly called "natural grace" in my previous posts) to God. In a world (as yours) where infants are sinners, God can't be accepted by them, and baptism is imposed by the parents. On the contrary, in an Orthodox view parents just follow the natural orientation of infants to God, which is the seed of faith, when they have their children baptised.
Hope this helps,
In Christ, Alex