For some reason, I was under the impression that I needed the new cards for the league, too. Oh, well. Doesn't really matter, though, as the decks that I had way back then wouldn't do anything now. I'll just use the theme decks that I bought to help me out a bit.
I loved getting the free cards from participating in the league. I have quite a few of them. (Though, we never really got any packs of cards...except maybe a few times.)