and oh yea; i've often wondered why the 1st 2 of the 10 commandments were as such:

1- thou shalt have no other gods before me
2- thou shalt not make unto thee any graven image, or any likeness of any thing that is in heaven above, or that is in the earth beneath, or that is in the water under the earth.
thou shalt not bow down thyself to them, nor serve them... *etc, etc*

but no more.

it is because it is one thing to worship other gods other than God himself. but even then, we must NOT set up any image, in any sort of fashion or form, and worship them, even if they are revered people/saints/angels in god's kingdom.

we must NOT pray to the saints, expecting them to intercede to god on our behalf.
we must NOT pray to the virgin mary, that she might interact w/god for us.

the only person we can come to is jesus, and that is on no coincidence that he was god incarnate, or basically God himself. (on top of many other reasons, like having come in sinful flesh, being our eternal high priest)

why was the old testament established if it was shown to not work? because it was created to show our need for a savior. romans points this out perfectly. would we know we were guilty of coveting if there was not a perfect law which stated in plain english, "do not covet?" but through this law, we find not salvation, but the need of a saviour. and from that saviour, we find salvation.