Forum:Using an older version of a card?

After getting back into the game after many years I have got some new cards that have different card texts. The simplest real example I have is "Ring of Magnetism". I have 2 copies of this card, one older and one newer but I want to use both in my deck, even if it means regarding them both as the newer version. So...

Can I use the older card as it is printed? Or can it be treated with the new text? Or is exempt from tournament use?

Also, is there a list of cards that have changed? Thanks.