It really hasn't been preserved very well, especialy the English versions. I had found a history of it awhile back and was astonished at the changes it has undergone in English.
The original Old English form was:
Fæder ure þu þe eart on heofonum si þin nama gehalgod tobecume þin rice gewurþe þin willa on eorðan swa swa on heofonum urne gedæghwamlican hlaf syle us to dæg and forgyf us ure gyltas swa swa we forgyfað urum gyltendum and ne gelæd þu us on costnunge ac alys us of yfele soþlice.
As English developed that became:
Oure fadir þat art in heuenes halwid be þi name;
þi reume or kyngdom come to be.
Be þi wille don in herþe as it is doun in heuene.
yeue to us today oure eche dayes bred.
And foryeue to us oure dettis þat is oure synnys as we foryeuen to oure dettouris þat is to men þat han synned in us.
And lede us not into temptacion but delyuere us from euyl.
By 1611 English began to resemble todays English and the popular form was:
Our father which art in heauen,
hallowed be thy name.
Thy kingdom come.
Thy will be done in earth as it is in heauen.
Giue us this day our daily bread.
And forgiue us our debts as we forgiue our debters.
And lead us not into temptation,
but deliuer us from euill.
Amen.
In the 1700s the last phrase was added and it became the now familiar:
Our Father which art in heaven, Hallowed be thy name. Thy kingdom come. Thy will be done in earth, as it is in heaven. Give us this day our daily bread. And forgive us our debts, as we forgive our debtors. And lead us not into temptation, but deliver us from evil: For thine is the kingdom, and the power, and the glory, for ever. Amen.
In 1963 another version came about, that may eventualy replace todays popular version:
Our Heavenly Father, may your name be honored;
May your kingdom come, and your will be done on earth as it is in Heaven.
Give us this day the bread we need,
Forgive us what we owe to you, as we have also forgiven those who owe anything to us.
Keep us clear of temptation, and save us from evil.
The source for this is the same link I posted above:
http://www.thenazareneway.com/lords_prayer.htm