New computer: do I have to buy the games again?

if you haven't already download Origin to your computer  log into your Origin from the shortcut icon with the email and password you use for your account  right click download

the sims 3 and origin use the same email and password alos if the games are regestired in the Sims 3 they auto reg in Origin and vice versa

please also take note the layout of the games has changed in Origin if your games are missing after that you must contact CS

store DLC items hair/clothes/worlds/sets download and install from the sims 3 account-my store account-purchase history

http://answers.ea.com/t5/The-Sims-3/FAQ-New-Origin-Layout-for-The-Sims-3-Expansion-Packs/m-p/4641393...

http://help.ea.com/en/contact-us/new/

  https://www.origin.com/en-us/download