To celebrate the ten year anniversary of The Sims 2, EA are offering the entire game collection (including all the Expansion and Stuff packs) for free.
To claim the offer, you must have Origin account and the Origin client installed. Next, go to the ‘Games‘ tab and click on ‘Redeem Product Code.’ Insert the code “I-LOVE-THE-SIMS” and the entire Ultimate Collection will be added to your game library.
EA’s help site has more in depth instructions if you get stuck. There’s also a second promotion running right now, in which EA is offering a free copy of Peggle.